diff --git a/web/source/css/_colors.css b/web/source/css/_colors.css
index 82028dce..70c12486 100644
--- a/web/source/css/_colors.css
+++ b/web/source/css/_colors.css
@@ -46,6 +46,7 @@ $blue3: #89caff; /* hover/selected accent to $blue2, can be used with $gray1 (7.
 
 $error1: #860000; /* Error border/foreground text, can be used with $error2 (5.0), $white1 (10), $white2 (5.1) */
 $error2: #ff9796; /* Error background text, can be used with $error1 (5.0), $gray1 (6.6), $gray2 (5.3), $gray3 (4.8) */
+$error3: #dd2c2c; /* Error button background text, can be used with $white1 (4.51) */
 $error-link: #185F8C; /* Error link text, can be used with $error2 (5.54) */
 
 $fg: $white1;
@@ -69,9 +70,9 @@ $button-bg: $blue2;
 $button-fg: $gray1;
 $button-hover-bg: $blue3;
 
-$button-danger-bg: $orange1;
-$button-danger-fg: $gray1;
-$button-danger-hover-bg: $orange2;
+$button-danger-bg: $error3;
+$button-danger-fg: $white1;
+$button-danger-hover-bg: $error2;
 
 $toot-focus-bg: $gray5;
 $toot-unfocus-bg: $gray2;
diff --git a/web/source/css/base.css b/web/source/css/base.css
index 760189be..73014de8 100644
--- a/web/source/css/base.css
+++ b/web/source/css/base.css
@@ -172,6 +172,16 @@ main {
 		}
 	}
 
+	&:disabled {
+		color: $white2;
+		background: $gray2;
+		cursor: auto;
+
+		&:hover {
+			background: $gray3;
+		}
+	}
+
 	&:hover {
 		background: $button-hover-bg;
 	}
diff --git a/web/source/index.js b/web/source/index.js
index 90ee5a4e..a96e663c 100644
--- a/web/source/index.js
+++ b/web/source/index.js
@@ -66,7 +66,6 @@ skulk({
 			],
 		},
 		settings: {
-			debug: false,
 			entryFile: "settings",
 			outputFile: "settings.js",
 			prodCfg: prodCfg,
diff --git a/web/source/settings/admin/emoji/category-select.jsx b/web/source/settings/admin/emoji/category-select.jsx
new file mode 100644
index 00000000..3a2ace89
--- /dev/null
+++ b/web/source/settings/admin/emoji/category-select.jsx
@@ -0,0 +1,96 @@
+/*
+	 GoToSocial
+	 Copyright (C) 2021-2022 GoToSocial Authors admin@gotosocial.org
+
+	 This program is free software: you can redistribute it and/or modify
+	 it under the terms of the GNU Affero General Public License as published by
+	 the Free Software Foundation, either version 3 of the License, or
+	 (at your option) any later version.
+
+	 This program is distributed in the hope that it will be useful,
+	 but WITHOUT ANY WARRANTY; without even the implied warranty of
+	 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+	 GNU Affero General Public License for more details.
+
+	 You should have received a copy of the GNU Affero General Public License
+	 along with this program.  If not, see <http://www.gnu.org/licenses/>.
+*/
+
+"use strict";
+
+const React = require("react");
+const splitFilterN = require("split-filter-n");
+const syncpipe = require('syncpipe');
+const { matchSorter } = require("match-sorter");
+
+const query = require("../../lib/query");
+
+const ComboBox = require("../../components/combo-box");
+
+function useEmojiByCategory(emoji) {
+	// split all emoji over an object keyed by the category names (or Unsorted)
+	return React.useMemo(() => splitFilterN(
+		emoji,
+		[],
+		(entry) => entry.category ?? "Unsorted"
+	), [emoji]);
+}
+
+function CategorySelect({value, categoryState, setIsNew=() => {}, children}) {
+	const {
+		data: emoji = [],
+		isLoading,
+		isSuccess,
+		error
+	} = query.useGetAllEmojiQuery({filter: "domain:local"});
+
+	const emojiByCategory = useEmojiByCategory(emoji);
+
+	const categories = React.useMemo(() => new Set(Object.keys(emojiByCategory)), [emojiByCategory]);
+
+	// data used by the ComboBox element to select an emoji category
+	const categoryItems = React.useMemo(() => {
+		return syncpipe(emojiByCategory, [
+			(_) => Object.keys(_),            // just emoji category names
+			(_) => matchSorter(_, value, {threshold: matchSorter.rankings.NO_MATCH}),  // sorted by complex algorithm
+			(_) => _.map((categoryName) => [  // map to input value, and selectable element with icon
+				categoryName,
+				<>
+					<img src={emojiByCategory[categoryName][0].static_url} aria-hidden="true"></img>
+					{categoryName}
+				</>
+			])
+		]);
+	}, [emojiByCategory, value]);
+
+	React.useEffect(() => {
+		if (value != undefined && isSuccess && value.trim().length > 0) {
+			setIsNew(!categories.has(value.trim()));
+		}
+	}, [categories, value, setIsNew, isSuccess]);
+
+	if (error) { // fall back to plain text input, but this would almost certainly have caused a bigger error message elsewhere
+		return (
+			<>
+				<input type="text" placeholder="e.g., reactions" onChange={(e) => {categoryState.value = e.target.value;}}/>;
+			</>
+		);
+	} else if (isLoading) {
+		return <input type="text" value="Loading categories..." disabled={true}/>;
+	}
+
+	return (
+		<ComboBox
+			state={categoryState}
+			items={categoryItems}
+			label="Category"
+			placeHolder="e.g., reactions"
+			children={children}
+		/>
+	);
+}
+
+module.exports = {
+	useEmojiByCategory,
+	CategorySelect
+};
\ No newline at end of file
diff --git a/web/source/settings/admin/emoji/detail.js b/web/source/settings/admin/emoji/detail.js
index cc0f8e73..26608471 100644
--- a/web/source/settings/admin/emoji/detail.js
+++ b/web/source/settings/admin/emoji/detail.js
@@ -22,48 +22,130 @@ const React = require("react");
 
 const { useRoute, Link, Redirect } = require("wouter");
 
-const BackButton = require("../../components/back-button");
+const { CategorySelect } = require("./category-select");
+const { useComboBoxInput, useFileInput } = require("../../components/form");
 
 const query = require("../../lib/query");
+const FakeToot = require("../../components/fake-toot");
 
 const base = "/settings/admin/custom-emoji";
 
-/* We wrap the component to generate formFields with a setter depending on the domain
-	 if formFields() is used inside the same component that is re-rendered with their state,
-	 inputs get re-created on every change, causing them to lose focus, and bad performance
-*/
-module.exports = function EmojiDetailWrapped() {
-	let [_match, {emojiId}] = useRoute(`${base}/:emojiId`);
-	const {currentData: emoji, isLoading, error} = query.useGetEmojiQuery(emojiId);
-
-	return (<>
-		{error && <div className="error accent">{error.status}: {error.data.error}</div>}
-		{isLoading
-			? "Loading..."
-			: <EmojiDetail emoji={emoji}/>
-		}
-	</>);
+module.exports = function EmojiDetailRoute() {
+	let [_match, params] = useRoute(`${base}/:emojiId`);
+	if (params?.emojiId == undefined) {
+		return <Redirect to={base}/>;
+	} else {
+		return (
+			<div className="emoji-detail">
+				<Link to={base}><a>&lt; go back</a></Link>
+				<EmojiDetailData emojiId={params.emojiId}/>
+			</div>
+		);
+	}
 };
 
+function EmojiDetailData({emojiId}) {
+	const {currentData: emoji, isLoading, error} = query.useGetEmojiQuery(emojiId);
+
+	if (error) {
+		return (
+			<div className="error accent">
+				{error.status}: {error.data.error}
+			</div>
+		);
+	} else if (isLoading) {
+		return "Loading...";
+	} else {
+		return <EmojiDetail emoji={emoji}/>;
+	}
+}
+
 function EmojiDetail({emoji}) {
-	if (emoji == undefined) {
-		return (<>
-			<Link to={base}>
-				<a className="button">go back</a>
-			</Link>
-		</>);
+	const [modifyEmoji, modifyResult] = query.useEditEmojiMutation();
+
+	const [isNewCategory, setIsNewCategory] = React.useState(false);
+
+	const [categoryState, _resetCategory, { category }] = useComboBoxInput("category", {defaultValue: emoji.category});
+
+	const [onFileChange, _resetFile, { image, imageURL, imageInfo }] = useFileInput("image", {
+		withPreview: true,
+		maxSize: 50 * 1024
+	});
+
+	function modifyCategory() {
+		modifyEmoji({id: emoji.id, category: category.trim()});
 	}
 
+	function modifyImage() {
+		modifyEmoji({id: emoji.id, image: image});
+	}
+
+	React.useEffect(() => {
+		if (category != emoji.category && !categoryState.open && !isNewCategory && emoji.category != undefined) {
+			console.log("updating to", category);
+			modifyEmoji({id: emoji.id, category: category.trim()});
+		}
+	}, [isNewCategory, category, categoryState.open, emoji.category, emoji.id, modifyEmoji]);
+
 	return (
-		<div>
-			<h1><BackButton to={base}/> Custom Emoji: {emoji.shortcode}</h1>
-			<DeleteButton id={emoji.id}/>
-			<p>
-				Editing custom emoji isn&apos;t implemented yet.<br/>
-				<a target="_blank" rel="noreferrer" href="https://github.com/superseriousbusiness/gotosocial/issues/797">View implementation progress.</a>
-			</p>
-			<img src={emoji.url} alt={emoji.shortcode} title={`:${emoji.shortcode}:`}/>
-		</div>
+		<>
+			<div className="emoji-header">
+				<img src={emoji.url} alt={emoji.shortcode} title={emoji.shortcode}/>
+				<div>
+					<h2>{emoji.shortcode}</h2>
+					<DeleteButton id={emoji.id}/>
+				</div>
+			</div>
+
+			<div className="left-border">
+				<h2>Modify this emoji {modifyResult.isLoading && "(processing..)"}</h2>
+
+				{modifyResult.error && <div className="error">
+					{modifyResult.error.status}: {modifyResult.error.data.error}
+				</div>}
+
+				<div className="update-category">
+					<CategorySelect
+						value={category}
+						categoryState={categoryState}
+						setIsNew={setIsNewCategory}
+					>
+						<button style={{visibility: (isNewCategory ? "initial" : "hidden")}} onClick={modifyCategory}>
+							Create
+						</button>
+					</CategorySelect>
+				</div>
+
+				<div className="update-image">
+					<b>Image</b>
+					<div className="form-field file">
+						<label className="file-input button" htmlFor="image">
+							Browse
+						</label>
+						{imageInfo}
+						<input
+							className="hidden"
+							type="file"
+							id="image"
+							name="Image"
+							accept="image/png,image/gif"
+							onChange={onFileChange}
+						/>
+					</div>
+
+					<button onClick={modifyImage} disabled={image == undefined}>Replace image</button>
+
+					<FakeToot>
+						Look at this new custom emoji <img
+							className="emoji"
+							src={imageURL ?? emoji.url}
+							title={`:${emoji.shortcode}:`}
+							alt={emoji.shortcode}
+						/> isn&apos;t it cool?
+					</FakeToot>
+				</div>
+			</div>
+		</>
 	);
 }
 
@@ -71,9 +153,9 @@ function DeleteButton({id}) {
 	// TODO: confirmation dialog?
 	const [deleteEmoji, deleteResult] = query.useDeleteEmojiMutation();
 
-	let text = "Delete this emoji";
+	let text = "Delete";
 	if (deleteResult.isLoading) {
-		text = "processing...";
+		text = "Deleting...";
 	}
 
 	if (deleteResult.isSuccess) {
@@ -81,6 +163,6 @@ function DeleteButton({id}) {
 	}
 
 	return (
-		<button onClick={() => deleteEmoji(id)} disabled={deleteResult.isLoading}>{text}</button>
+		<button className="danger" onClick={() => deleteEmoji(id)} disabled={deleteResult.isLoading}>{text}</button>
 	);
 }
\ No newline at end of file
diff --git a/web/source/settings/admin/emoji/new-emoji.js b/web/source/settings/admin/emoji/new-emoji.js
index 65dc5213..8cd604c0 100644
--- a/web/source/settings/admin/emoji/new-emoji.js
+++ b/web/source/settings/admin/emoji/new-emoji.js
@@ -20,11 +20,9 @@
 
 const Promise = require('bluebird');
 const React = require("react");
-const { matchSorter } = require("match-sorter");
 
 const FakeToot = require("../../components/fake-toot");
 const MutateButton = require("../../components/mutation-button");
-const ComboBox = require("../../components/combo-box");
 
 const {
 	useTextInput,
@@ -33,9 +31,9 @@ const {
 } = require("../../components/form");
 
 const query = require("../../lib/query");
-const syncpipe = require('syncpipe');
+const { CategorySelect } = require('./category-select');
 
-module.exports = function NewEmojiForm({ emoji, emojiByCategory }) {
+module.exports = function NewEmojiForm({ emoji }) {
 	const emojiCodes = React.useMemo(() => {
 		return new Set(emoji.map((e) => e.shortcode));
 	}, [emoji]);
@@ -57,21 +55,6 @@ module.exports = function NewEmojiForm({ emoji, emojiByCategory }) {
 
 	const [categoryState, resetCategory, { category }] = useComboBoxInput("category");
 
-	// data used by the ComboBox element to select an emoji category
-	const categoryItems = React.useMemo(() => {
-		return syncpipe(emojiByCategory, [
-			(_) => Object.keys(_),            // just emoji category names
-			(_) => matchSorter(_, category),  // sorted by complex algorithm
-			(_) => _.map((categoryName) => [  // map to input value, and selectable element with icon
-				categoryName,
-				<>
-					<img src={emojiByCategory[categoryName][0].static_url} aria-hidden="true"></img>
-					{categoryName}
-				</>
-			])
-		]);
-	}, [emojiByCategory, category]);
-
 	React.useEffect(() => {
 		if (shortcode.length == 0) {
 			if (image != undefined) {
@@ -152,11 +135,9 @@ module.exports = function NewEmojiForm({ emoji, emojiByCategory }) {
 					/>
 				</div>
 
-				<ComboBox
-					state={categoryState}
-					items={categoryItems}
-					label="Category"
-					placeHolder="e.g., reactions"
+				<CategorySelect
+					value={category}
+					categoryState={categoryState}
 				/>
 
 				<MutateButton text="Upload emoji" result={result} />
diff --git a/web/source/settings/admin/emoji/overview.js b/web/source/settings/admin/emoji/overview.js
index 15891a5e..b8ac87a0 100644
--- a/web/source/settings/admin/emoji/overview.js
+++ b/web/source/settings/admin/emoji/overview.js
@@ -20,11 +20,11 @@
 
 const React = require("react");
 const {Link} = require("wouter");
-const splitFilterN = require("split-filter-n");
 
 const NewEmojiForm = require("./new-emoji");
 
 const query = require("../../lib/query");
+const { useEmojiByCategory } = require("./category-select");
 
 const base = "/settings/admin/custom-emoji";
 
@@ -35,13 +35,6 @@ module.exports = function EmojiOverview() {
 		error
 	} = query.useGetAllEmojiQuery({filter: "domain:local"});
 
-	// split all emoji over an object keyed by the category names (or Unsorted)
-	const emojiByCategory = React.useMemo(() => splitFilterN(
-		emoji,
-		[],
-		(entry) => entry.category ?? "Unsorted"
-	), [emoji]);
-
 	return (
 		<>
 			<h1>Custom Emoji</h1>
@@ -51,15 +44,17 @@ module.exports = function EmojiOverview() {
 			{isLoading
 				? "Loading..."
 				: <>
-					<EmojiList emoji={emoji} emojiByCategory={emojiByCategory}/>
-					<NewEmojiForm emoji={emoji} emojiByCategory={emojiByCategory}/>
+					<EmojiList emoji={emoji}/>
+					<NewEmojiForm emoji={emoji}/>
 				</>
 			}
 		</>
 	);
 };
 
-function EmojiList({emoji, emojiByCategory}) {
+function EmojiList({emoji}) {
+	const emojiByCategory = useEmojiByCategory(emoji);
+
 	return (
 		<div>
 			<h2>Overview</h2>
diff --git a/web/source/settings/components/combo-box.jsx b/web/source/settings/components/combo-box.jsx
index 1e629389..d69df55b 100644
--- a/web/source/settings/components/combo-box.jsx
+++ b/web/source/settings/components/combo-box.jsx
@@ -26,16 +26,19 @@ const {
 	ComboboxPopover,
 } = require("ariakit/combobox");
 
-module.exports = function ComboBox({state, items, label, placeHolder}) {
+module.exports = function ComboBox({state, items, label, placeHolder, children}) {
 	return (
 		<div className="form-field combobox-wrapper">
 			<label>
 				{label}
-				<Combobox
-					state={state}
-					placeholder={placeHolder}
-					className="combobox input"
-				/>
+				<div className="row">
+					<Combobox
+						state={state}
+						placeholder={placeHolder}
+						className="combobox input"
+					/>
+					{children}
+				</div>
 			</label>
 			<ComboboxPopover state={state} className="popover">
 				{items.map(([key, value]) => (
diff --git a/web/source/settings/components/form/combobox.jsx b/web/source/settings/components/form/combobox.jsx
index 6ab235ed..d21a8c3f 100644
--- a/web/source/settings/components/form/combobox.jsx
+++ b/web/source/settings/components/form/combobox.jsx
@@ -20,11 +20,15 @@
 
 const { useComboboxState } = require("ariakit/combobox");
 
-module.exports = function useComboBoxInput({name, Name}, {validator} = {}) {
-	const state = useComboboxState({ gutter: 0, sameWidth: true });
+module.exports = function useComboBoxInput({name, Name}, {validator, defaultValue} = {}) {
+	const state = useComboboxState({
+		defaultValue,
+		gutter: 0,
+		sameWidth: true
+	});
 
 	function reset() {
-		state.value = "";
+		state.setValue("");
 	}
 
 	return [
diff --git a/web/source/settings/lib/query/custom-emoji.js b/web/source/settings/lib/query/custom-emoji.js
index a26da75c..fa2a08db 100644
--- a/web/source/settings/lib/query/custom-emoji.js
+++ b/web/source/settings/lib/query/custom-emoji.js
@@ -54,6 +54,23 @@ const endpoints = (build) => ({
 				? [{type: "Emojis", id: "LIST"}, {type: "Emojis", id: res.id}]
 				: [{type: "Emojis", id: "LIST"}]
 	}),
+	editEmoji: build.mutation({
+		query: ({id, ...patch}) => {
+			return {
+				method: "PATCH",
+				url: `/api/v1/admin/custom_emojis/${id}`,
+				asForm: true,
+				body: {
+					type: "modify",
+					...patch
+				}
+			};
+		},
+		invalidatesTags: (res) => 
+			res
+				? [{type: "Emojis", id: "LIST"}, {type: "Emojis", id: res.id}]
+				: [{type: "Emojis", id: "LIST"}]
+	}),
 	deleteEmoji: build.mutation({
 		query: (id) => ({
 			method: "DELETE",
diff --git a/web/source/settings/style.css b/web/source/settings/style.css
index 2a32fc0a..7922a405 100644
--- a/web/source/settings/style.css
+++ b/web/source/settings/style.css
@@ -544,4 +544,56 @@ span.form-info {
 .combobox-item[data-active-item] {
   background: $button-hover-bg;
   color: hsl(204 20% 100%);
+}
+
+.row {
+	display: flex;
+}
+
+.emoji-detail {
+	display: flex;
+	flex-direction: column;
+	gap: 1rem !important;
+
+	& > a {
+		align-self: flex-start;
+	}
+
+	.emoji-header {
+		display: flex;
+		align-items: center;
+		gap: 0.5rem;
+
+		img {
+			height: 8.5rem;
+			width: 8.5rem;
+			border: 0.2rem solid $border-accent;
+			object-fit: contain;
+			padding: 0.5rem;
+		}
+	}
+
+	.update-category {
+		margin-bottom: 1rem;
+		.combobox-wrapper button {
+			font-size: 1rem;
+			margin: 0.15rem 0;
+		}
+	
+		.row {
+			margin-top: 0.4rem;
+			gap: 0.5rem;
+		}
+	}
+
+	.update-image {
+		display: flex;
+		flex-direction: column;
+		gap: 0.5rem;
+	}
+}
+
+.left-border {
+	border-left: 0.2rem solid $border-accent;
+	padding-left: 0.4rem;
 }
\ No newline at end of file