diff --git a/web/src/stream_popover.js b/web/src/stream_popover.js
index b8cabf1e8b..8d660f83d7 100644
--- a/web/src/stream_popover.js
+++ b/web/src/stream_popover.js
@@ -680,8 +680,8 @@ export function register_stream_handlers() {
     // Mark all messages as read
     $("body").on("click", "#mark_all_messages_as_read", (e) => {
         hide_all_messages_popover();
-        unread_ops.mark_all_as_read();
         e.stopPropagation();
+        unread_ops.confirm_mark_all_as_read();
     });
 
     // Unstar all messages
diff --git a/web/src/unread_ops.js b/web/src/unread_ops.js
index 1e7be5cd52..b0949335e9 100644
--- a/web/src/unread_ops.js
+++ b/web/src/unread_ops.js
@@ -1,7 +1,11 @@
 import $ from "jquery";
 
+import render_confirm_mark_all_as_read from "../templates/confirm_dialog/confirm_mark_all_as_read.hbs";
+
 import * as blueslip from "./blueslip";
 import * as channel from "./channel";
+import * as confirm_dialog from "./confirm_dialog";
+import * as dialog_widget from "./dialog_widget";
 import {$t_html} from "./i18n";
 import * as loading from "./loading";
 import * as message_flags from "./message_flags";
@@ -27,6 +31,17 @@ let loading_indicator_displayed = false;
 const INITIAL_BATCH_SIZE = 1000;
 const FOLLOWUP_BATCH_SIZE = 1000;
 
+export function confirm_mark_all_as_read() {
+    const html_body = render_confirm_mark_all_as_read();
+
+    confirm_dialog.launch({
+        html_heading: $t_html({defaultMessage: "Mark all messages as read?"}),
+        html_body,
+        on_click: mark_all_as_read,
+        loading_spinner: true,
+    });
+}
+
 export function mark_all_as_read(args = {}) {
     args = {
         // We use an anchor of "oldest", not "first_unread", because
@@ -116,6 +131,7 @@ export function mark_all_as_read(args = {}) {
                     blueslip.log("Cleared old_unreads_missing after bankruptcy.");
                 }
             }
+            dialog_widget.close_modal();
         },
         error(xhr) {
             // If we hit the rate limit, just continue without showing any error.
@@ -127,6 +143,7 @@ export function mark_all_as_read(args = {}) {
                 // the user needs to know that our operation failed.
                 blueslip.error("Failed to mark messages as read: " + xhr.responseText);
             }
+            dialog_widget.hide_dialog_spinner();
         },
     });
 }
diff --git a/web/templates/confirm_dialog/confirm_mark_all_as_read.hbs b/web/templates/confirm_dialog/confirm_mark_all_as_read.hbs
new file mode 100644
index 0000000000..ada6a582a1
--- /dev/null
+++ b/web/templates/confirm_dialog/confirm_mark_all_as_read.hbs
@@ -0,0 +1,5 @@
+<p>
+    {{#tr}}
+        Are you sure you want to mark all messages as read? This action cannot be undone.
+    {{/tr}}
+</p>