diff --git a/app/javascript/flavours/glitch/components/alt_text_badge.tsx b/app/javascript/flavours/glitch/components/alt_text_badge/index.tsx
similarity index 54%
rename from app/javascript/flavours/glitch/components/alt_text_badge.tsx
rename to app/javascript/flavours/glitch/components/alt_text_badge/index.tsx
index 93d8d8b753..586dc2415f 100644
--- a/app/javascript/flavours/glitch/components/alt_text_badge.tsx
+++ b/app/javascript/flavours/glitch/components/alt_text_badge/index.tsx
@@ -1,6 +1,6 @@
-import { useState, useCallback, useRef, useId } from 'react';
+import { useState, useCallback, useRef, useId, Fragment } from 'react';
 
-import { FormattedMessage } from 'react-intl';
+import { FormattedMessage, useIntl } from 'react-intl';
 
 import type {
   OffsetValue,
@@ -8,24 +8,37 @@ import type {
 } from 'react-overlays/esm/usePopper';
 import Overlay from 'react-overlays/Overlay';
 
+import CloseIcon from '@/material-icons/400-24px/close.svg?react';
 import { useSelectableClick } from 'flavours/glitch/hooks/useSelectableClick';
 
+import { IconButton } from '../icon_button';
+
+import classes from './styles.module.scss';
+
 const offset = [0, 4] as OffsetValue;
 const popperConfig = { strategy: 'fixed' } as UsePopperOptions;
 
 export const AltTextBadge: React.FC<{ description: string }> = ({
   description,
 }) => {
-  const accessibilityId = useId();
-  const anchorRef = useRef<HTMLButtonElement>(null);
+  const intl = useIntl();
+  const uniqueId = useId();
+  const popoverId = `${uniqueId}-popover`;
+  const titleId = `${uniqueId}-title`;
+  const buttonRef = useRef<HTMLButtonElement>(null);
+  const popoverRef = useRef<HTMLDivElement>(null);
   const [open, setOpen] = useState(false);
 
   const handleClick = useCallback(() => {
     setOpen((v) => !v);
+    setTimeout(() => {
+      popoverRef.current?.focus();
+    }, 0);
   }, [setOpen]);
 
   const handleClose = useCallback(() => {
     setOpen(false);
+    buttonRef.current?.focus();
   }, [setOpen]);
 
   const [handleMouseDown, handleMouseUp] = useSelectableClick(handleClose);
@@ -34,11 +47,12 @@ export const AltTextBadge: React.FC<{ description: string }> = ({
     <>
       <button
         type='button'
-        ref={anchorRef}
+        ref={buttonRef}
         className='media-gallery__alt__label'
         onClick={handleClick}
         aria-expanded={open}
-        aria-controls={accessibilityId}
+        aria-controls={popoverId}
+        aria-haspopup='dialog'
       >
         ALT
       </button>
@@ -47,7 +61,7 @@ export const AltTextBadge: React.FC<{ description: string }> = ({
         rootClose
         onHide={handleClose}
         show={open}
-        target={anchorRef}
+        target={buttonRef}
         placement='top-end'
         flip
         offset={offset}
@@ -57,17 +71,34 @@ export const AltTextBadge: React.FC<{ description: string }> = ({
           <div {...props} className='hover-card-controller'>
             <div // eslint-disable-line jsx-a11y/no-noninteractive-element-interactions
               className='info-tooltip dropdown-animation'
-              role='region'
-              id={accessibilityId}
+              role='dialog'
+              aria-labelledby={titleId}
+              ref={popoverRef}
+              id={popoverId}
               onMouseDown={handleMouseDown}
               onMouseUp={handleMouseUp}
+              // eslint-disable-next-line jsx-a11y/no-noninteractive-tabindex
+              tabIndex={0}
             >
-              <h4>
+              <h4 id={titleId}>
                 <FormattedMessage
                   id='alt_text_badge.title'
                   defaultMessage='Alt text'
+                  tagName={Fragment}
                 />
               </h4>
+
+              <IconButton
+                title={intl.formatMessage({
+                  id: 'lightbox.close',
+                  defaultMessage: 'Close',
+                })}
+                icon='close'
+                iconComponent={CloseIcon}
+                onClick={handleClose}
+                className={classes.closeButton}
+              />
+
               <p>{description}</p>
             </div>
           </div>
diff --git a/app/javascript/flavours/glitch/components/alt_text_badge/styles.module.scss b/app/javascript/flavours/glitch/components/alt_text_badge/styles.module.scss
new file mode 100644
index 0000000000..1b7d5ec788
--- /dev/null
+++ b/app/javascript/flavours/glitch/components/alt_text_badge/styles.module.scss
@@ -0,0 +1,17 @@
+.closeButton {
+  position: absolute;
+  top: 5px;
+  inset-inline-end: 2px;
+  padding: 10px;
+
+  --default-icon-color: var(--color-text-on-media);
+  --default-bg-color: transparent;
+  --hover-icon-color: var(--color-text-on-media);
+  --hover-bg-color: rgb(from var(--color-text-on-media) r g b / 10%);
+  --focus-outline-color: var(--color-text-on-media);
+
+  svg {
+    width: 20px;
+    height: 20px;
+  }
+}
diff --git a/app/javascript/flavours/glitch/styles/mastodon/components.scss b/app/javascript/flavours/glitch/styles/mastodon/components.scss
index 117806878b..484c4d3d65 100644
--- a/app/javascript/flavours/glitch/styles/mastodon/components.scss
+++ b/app/javascript/flavours/glitch/styles/mastodon/components.scss
@@ -285,6 +285,7 @@
   --default-bg-color: transparent;
   --hover-icon-color: var(--color-text-primary);
   --hover-bg-color: var(--color-bg-brand-softer);
+  --focus-outline-color: var(--color-text-brand);
 
   display: inline-flex;
   color: var(--default-icon-color);
@@ -313,7 +314,7 @@
   }
 
   &:focus-visible {
-    outline: 2px solid var(--color-text-brand);
+    outline: 2px solid var(--focus-outline-color);
   }
 
   &.disabled {
@@ -5160,6 +5161,13 @@ a.status-card {
         background-color: rgb(from var(--color-bg-media-base) r g b / 90%);
       }
     }
+
+    &:focus-visible {
+      .spoiler-button__overlay__label {
+        outline: 2px solid var(--color-text-on-media);
+        outline-offset: -4px;
+      }
+    }
   }
 }
 
@@ -7380,6 +7388,13 @@ img.modal-warning {
     font-size: 14px;
     font-weight: 700;
     line-height: 20px;
+
+    &:focus-visible {
+      outline: none;
+      box-shadow:
+        inset 0 0 0 2px var(--color-text-on-media),
+        0 0 0 2px var(--color-bg-media);
+    }
   }
 }
 
@@ -7409,6 +7424,13 @@ img.modal-warning {
   cursor: pointer;
   pointer-events: auto;
 
+  &:focus-visible {
+    outline: none;
+    box-shadow:
+      inset 0 0 0 2px var(--color-text-on-media),
+      0 0 0 2px var(--color-bg-media);
+  }
+
   &--non-interactive {
     pointer-events: none;
   }
@@ -7433,6 +7455,16 @@ img.modal-warning {
   overflow-y: auto;
   z-index: 10;
 
+  &:focus-visible {
+    box-shadow:
+      var(--dropdown-shadow),
+      inset 0 0 0 2px var(--color-text-on-media);
+
+    // Extend background color for better visibility of the
+    // inset box-shadow "outline"
+    outline: 2px solid var(--color-bg-media);
+  }
+
   &--solid {
     color: var(--color-text-primary);
     background: var(--color-bg-primary);
@@ -7684,6 +7716,7 @@ img.modal-warning {
   color: var(--color-text-primary);
   position: relative;
   z-index: -1;
+  border-radius: inherit;
 
   &,
   img {
@@ -7732,6 +7765,23 @@ img.modal-warning {
     height: 100%;
     object-fit: cover;
   }
+
+  &:focus {
+    outline: none;
+    border-radius: inherit;
+  }
+
+  // Double focus outline for better visibility on photos
+  &:focus-visible::after {
+    content: '';
+    position: absolute;
+    inset: 2px;
+    z-index: 1;
+    border-radius: inherit;
+    border: 2px solid var(--color-text-on-inverted);
+    outline: 2px solid var(--color-bg-inverted);
+    pointer-events: none;
+  }
 }
 
 /* End Media Gallery */