diff --git a/packages/govuk-frontend/src/govuk/components/file-upload/_index.scss b/packages/govuk-frontend/src/govuk/components/file-upload/_index.scss
index 8e29966f99..6f785a276a 100644
--- a/packages/govuk-frontend/src/govuk/components/file-upload/_index.scss
+++ b/packages/govuk-frontend/src/govuk/components/file-upload/_index.scss
@@ -80,20 +80,20 @@
     z-index: 1;
   }
 
-  .govuk-file-upload__pseudo-button {
+  .govuk-file-upload-button__pseudo-button {
     width: auto;
     margin-right: govuk-spacing(2);
     margin-bottom: $govuk-border-width-form-element + 1;
     flex-shrink: 0;
   }
 
-  .govuk-file-upload__instruction {
+  .govuk-file-upload-button__instruction {
     margin-top: govuk-spacing(2) - ($govuk-border-width-form-element + 1);
     margin-bottom: 0;
     text-align: left;
   }
 
-  .govuk-file-upload__status {
+  .govuk-file-upload-button__status {
     display: block;
     margin-bottom: govuk-spacing(2);
     padding: govuk-spacing(3) govuk-spacing(2);
@@ -101,7 +101,7 @@
     text-align: left;
   }
 
-  .govuk-file-upload__button--empty .govuk-file-upload__status {
+  .govuk-file-upload-button--empty .govuk-file-upload-button__status {
     color: govuk-shade(govuk-colour("blue"), 60%);
     background-color: govuk-tint(govuk-colour("blue"), 70%);
   }
@@ -109,13 +109,13 @@
   // bugs documented with button using flex
   // https://github.com/philipwalton/flexbugs#flexbug-9
   // so we need a container here
-  .govuk-file-upload__pseudo-button-container {
+  .govuk-file-upload-button__pseudo-button-container {
     display: flex;
     align-items: baseline;
     flex-wrap: wrap;
   }
 
-  .govuk-file-upload__button {
+  .govuk-file-upload-button {
     width: 100%;
     // align the padding to be same as notification banner and error summary accounting for the thicker borders
     padding: (govuk-spacing(3) + $govuk-border-width - $file-upload-border-width);
@@ -128,55 +128,55 @@
     }
   }
 
-  .govuk-file-upload__button--empty {
+  .govuk-file-upload-button--empty {
     border-style: dashed;
     background-color: govuk-colour("white");
   }
 
-  .govuk-file-upload__button.govuk-file-upload__button--empty:hover {
+  .govuk-file-upload-button--empty:hover {
     background-color: govuk-colour("light-grey");
   }
 
-  .govuk-file-upload__button:disabled {
+  .govuk-file-upload-button:disabled {
     pointer-events: none;
     opacity: 0.5;
   }
 
-  .govuk-file-upload__button--dragging.govuk-file-upload__button,
+  .govuk-file-upload-button--dragging.govuk-file-upload-button,
   .govuk-file-upload__button:hover {
     background-color: govuk-tint(govuk-colour("mid-grey"), 20%);
   }
 
-  .govuk-file-upload__button--dragging.govuk-file-upload__button--empty {
+  .govuk-file-upload-button--dragging.govuk-file-upload-button--empty {
     background-color: govuk-colour("light-grey");
   }
 
-  .govuk-file-upload__button--dragging:not(:disabled) {
+  .govuk-file-upload-button--dragging:not(:disabled) {
     border-color: govuk-shade(govuk-colour("mid-grey"), 20%);
   }
 
-  .govuk-file-upload__button--dragging:not(:disabled) .govuk-file-upload__pseudo-button,
-  .govuk-file-upload__button:hover .govuk-file-upload__pseudo-button {
+  .govuk-file-upload-button--dragging:not(:disabled) .govuk-file-upload-button__pseudo-button,
+  .govuk-file-upload-button:hover .govuk-file-upload-button__pseudo-button {
     background-color: govuk-shade(govuk-colour("light-grey"), 10%);
   }
 
-  .govuk-file-upload__button--empty.govuk-file-upload__button--dragging:not(:disabled) .govuk-file-upload__status,
-  .govuk-file-upload__button--empty:hover .govuk-file-upload__status,
-  .govuk-file-upload__button--empty:focus .govuk-file-upload__status {
+  .govuk-file-upload-button--empty.govuk-file-upload-button--dragging:not(:disabled) .govuk-file-upload-button__status,
+  .govuk-file-upload-button--empty:hover .govuk-file-upload-button__status,
+  .govuk-file-upload-button--empty:focus .govuk-file-upload-button__status {
     background-color: govuk-tint(govuk-colour("blue"), 80%);
   }
 
-  .govuk-file-upload__button .govuk-file-upload__pseudo-button,
-  .govuk-file-upload__button--empty.govuk-file-upload__button--dragging .govuk-file-upload__pseudo-button {
+  .govuk-file-upload-button .govuk-file-upload-button__pseudo-button,
+  .govuk-file-upload-button--empty.govuk-file-upload-button--dragging .govuk-file-upload-button__pseudo-button {
     background-color: govuk-colour("white");
   }
 
-  .govuk-file-upload__button--empty .govuk-file-upload__pseudo-button {
+  .govuk-file-upload-button--empty .govuk-file-upload-button__pseudo-button {
     background-color: govuk-colour("light-grey");
   }
 
-  .govuk-file-upload__button:active,
-  .govuk-file-upload__button:focus {
+  .govuk-file-upload-button:active,
+  .govuk-file-upload-button:focus {
     border: $file-upload-border-width solid govuk-colour("black");
     outline: $govuk-focus-width solid $govuk-focus-colour;
     // Ensure outline appears outside of the element
@@ -190,17 +190,17 @@
     box-shadow: inset 0 0 0 $govuk-border-width-form-element;
   }
 
-  .govuk-file-upload__button--empty:active,
-  .govuk-file-upload__button--empty:focus {
+  .govuk-file-upload-button--empty:active,
+  .govuk-file-upload-button--empty:focus {
     background-color: govuk-colour("light-grey");
   }
 
-  .govuk-file-upload__button:focus .govuk-file-upload__pseudo-button {
+  .govuk-file-upload-button:focus .govuk-file-upload-button__pseudo-button {
     background-color: $govuk-focus-colour;
     box-shadow: 0 2px 0 govuk-colour("black");
   }
 
-  .govuk-file-upload__button:focus:hover .govuk-file-upload__pseudo-button {
+  .govuk-file-upload-button:focus:hover .govuk-file-upload-button__pseudo-button {
     border-color: $govuk-focus-colour;
     outline: 3px solid transparent;
     background-color: govuk-colour("light-grey");
diff --git a/packages/govuk-frontend/src/govuk/components/file-upload/file-upload.mjs b/packages/govuk-frontend/src/govuk/components/file-upload/file-upload.mjs
index 5f766b14b2..2d1c9c2b86 100644
--- a/packages/govuk-frontend/src/govuk/components/file-upload/file-upload.mjs
+++ b/packages/govuk-frontend/src/govuk/components/file-upload/file-upload.mjs
@@ -90,10 +90,10 @@ export class FileUpload extends ConfigurableComponent {
 
     // Create the file selection button
     const $button = document.createElement('button')
-    $button.classList.add('govuk-file-upload__button')
+    $button.classList.add('govuk-file-upload-button')
     $button.type = 'button'
     $button.id = this.id
-    $button.classList.add('govuk-file-upload__button--empty')
+    $button.classList.add('govuk-file-upload-button--empty')
 
     // Copy `aria-describedby` if present so hints and errors
     // are associated to the `<button>`
@@ -104,7 +104,7 @@ export class FileUpload extends ConfigurableComponent {
 
     // Create status element that shows what/how many files are selected
     const $status = document.createElement('span')
-    $status.className = 'govuk-body govuk-file-upload__status'
+    $status.className = 'govuk-body govuk-file-upload-button__status'
     $status.innerText = this.i18n.t('filesSelectedDefault')
 
     $button.appendChild($status)
@@ -117,11 +117,12 @@ export class FileUpload extends ConfigurableComponent {
     $button.appendChild(commaSpan)
 
     const containerSpan = document.createElement('span')
-    containerSpan.className = 'govuk-file-upload__pseudo-button-container'
+    containerSpan.className =
+      'govuk-file-upload-button__pseudo-button-container'
 
     const buttonSpan = document.createElement('span')
     buttonSpan.className =
-      'govuk-button govuk-button--secondary govuk-file-upload__pseudo-button'
+      'govuk-button govuk-button--secondary govuk-file-upload-button__pseudo-button'
     buttonSpan.innerText = this.i18n.t('selectFilesButton')
 
     containerSpan.appendChild(buttonSpan)
@@ -131,7 +132,8 @@ export class FileUpload extends ConfigurableComponent {
     containerSpan.insertAdjacentText('beforeend', ' ')
 
     const instructionSpan = document.createElement('span')
-    instructionSpan.className = 'govuk-body govuk-file-upload__instruction'
+    instructionSpan.className =
+      'govuk-body govuk-file-upload-button__instruction'
     instructionSpan.innerText = this.i18n.t('instruction')
 
     containerSpan.appendChild(instructionSpan)
@@ -227,10 +229,10 @@ export class FileUpload extends ConfigurableComponent {
           // to avoid repeated announcements on NVDA (2024.4) + Firefox (133)
           if (
             !this.$button.classList.contains(
-              'govuk-file-upload__button--dragging'
+              'govuk-file-upload-button--dragging'
             )
           ) {
-            this.$button.classList.add('govuk-file-upload__button--dragging')
+            this.$button.classList.add('govuk-file-upload-button--dragging')
             this.$input.classList.add('govuk-file-upload--dragging')
             this.$announcements.innerText = this.i18n.t('dropZoneEntered')
           }
@@ -240,7 +242,7 @@ export class FileUpload extends ConfigurableComponent {
         // left the drop zone when they enter the page but haven't reached yet
         // the file upload component
         if (
-          this.$button.classList.contains('govuk-file-upload__button--dragging')
+          this.$button.classList.contains('govuk-file-upload-button--dragging')
         ) {
           this.hideDropZone()
         }
@@ -252,7 +254,7 @@ export class FileUpload extends ConfigurableComponent {
    * Hides the dropzone once user has dropped files on the `<input>`
    */
   hideDropZone() {
-    this.$button.classList.remove('govuk-file-upload__button--dragging')
+    this.$button.classList.remove('govuk-file-upload-button--dragging')
     this.$input.classList.remove('govuk-file-upload--dragging')
     this.$announcements.innerText = this.i18n.t('dropZoneLeft')
   }
@@ -266,7 +268,7 @@ export class FileUpload extends ConfigurableComponent {
     if (fileCount === 0) {
       // If there are no files, show the default selection text
       this.$status.innerText = this.i18n.t('filesSelectedDefault')
-      this.$button.classList.add('govuk-file-upload__button--empty')
+      this.$button.classList.add('govuk-file-upload-button--empty')
     } else {
       if (
         // If there is 1 file, just show the file name
@@ -280,7 +282,7 @@ export class FileUpload extends ConfigurableComponent {
         })
       }
 
-      this.$button.classList.remove('govuk-file-upload__button--empty')
+      this.$button.classList.remove('govuk-file-upload-button--empty')
     }
   }
 
diff --git a/packages/govuk-frontend/src/govuk/components/file-upload/file-upload.puppeteer.test.js b/packages/govuk-frontend/src/govuk/components/file-upload/file-upload.puppeteer.test.js
index 8216448253..0501d203b0 100644
--- a/packages/govuk-frontend/src/govuk/components/file-upload/file-upload.puppeteer.test.js
+++ b/packages/govuk-frontend/src/govuk/components/file-upload/file-upload.puppeteer.test.js
@@ -8,9 +8,9 @@ const { getExamples } = require('@govuk-frontend/lib/components')
 
 const inputSelector = '.govuk-file-upload'
 const wrapperSelector = '.govuk-drop-zone'
-const buttonSelector = '.govuk-file-upload__button'
-const statusSelector = '.govuk-file-upload__status'
-const pseudoButtonSelector = '.govuk-file-upload__pseudo-button'
+const buttonSelector = '.govuk-file-upload-button'
+const statusSelector = '.govuk-file-upload-button__status'
+const pseudoButtonSelector = '.govuk-file-upload-button__pseudo-button'
 
 describe('/components/file-upload', () => {
   let examples
@@ -255,9 +255,9 @@ describe('/components/file-upload', () => {
         }
 
         const selectorDropzoneVisible =
-          '.govuk-file-upload__button.govuk-file-upload__button--dragging'
+          '.govuk-file-upload-button.govuk-file-upload-button--dragging'
         const selectorDropzoneHidden =
-          '.govuk-file-upload__button:not(.govuk-file-upload__button--dragging)'
+          '.govuk-file-upload-button:not(.govuk-file-upload-button--dragging)'
 
         beforeEach(async () => {
           await render(page, 'file-upload', examples.enhanced)
@@ -350,7 +350,7 @@ describe('/components/file-upload', () => {
         it('includes the label, the status, the pseudo button and instruction', async () => {
           await render(page, 'file-upload', examples.enhanced)
 
-          const $element = await page.$('.govuk-file-upload__button')
+          const $element = await page.$('.govuk-file-upload-button')
 
           const accessibleName = await getAccessibleName(page, $element)
           await expect(accessibleName.replaceAll(/\s+/g, ' ')).toBe(
@@ -361,7 +361,7 @@ describe('/components/file-upload', () => {
         it('includes the label, file name, pseudo button and instruction once a file is selected', async () => {
           await render(page, 'file-upload', examples.enhanced)
 
-          const $element = await page.$('.govuk-file-upload__button')
+          const $element = await page.$('.govuk-file-upload-button')
 
           const [fileChooser] = await Promise.all([
             page.waitForFileChooser(),
@@ -384,7 +384,7 @@ describe('/components/file-upload', () => {
             }
           })
 
-          const $element = await page.$('.govuk-file-upload__button')
+          const $element = await page.$('.govuk-file-upload-button')
 
           const [fileChooser] = await Promise.all([
             page.waitForFileChooser(),