diff --git a/devtools/client/framework/browser-toolbox/test/browser_browser_toolbox_ruleview_stylesheet.js b/devtools/client/framework/browser-toolbox/test/browser_browser_toolbox_ruleview_stylesheet.js
index 88583b76b40a..60f30b44b447 100644
--- a/devtools/client/framework/browser-toolbox/test/browser_browser_toolbox_ruleview_stylesheet.js
+++ b/devtools/client/framework/browser-toolbox/test/browser_browser_toolbox_ruleview_stylesheet.js
@@ -32,6 +32,7 @@ add_task(async function () {
     selectNode,
     // selectNodeInFrames depends on selectNode, getNodeFront, getNodeFrontInFrames.
     selectNodeInFrames,
+    waitUntil,
   });
 
   // This is a simple test page, which contains a <div> with a CSS rule `color: red`
@@ -63,6 +64,7 @@ add_task(async function () {
 
     info("Retrieve the sourceLabel for the rule at index 1");
     const ruleView = inspector.getPanel("ruleview").view;
+    await waitUntil(() => getRuleViewLinkByIndex(ruleView, 1));
     const sourceLabelEl = getRuleViewLinkByIndex(ruleView, 1).querySelector(
       ".ruleview-rule-source-label"
     );
diff --git a/devtools/client/inspector/rules/rules.js b/devtools/client/inspector/rules/rules.js
index d8bfe03986c7..da6af7bfa964 100644
--- a/devtools/client/inspector/rules/rules.js
+++ b/devtools/client/inspector/rules/rules.js
@@ -2077,7 +2077,10 @@ function RuleViewTool(inspector, window) {
   this.inspector.styleChangeTracker.on("style-changed", this.refresh);
 
   this.inspector.commands.resourceCommand.watchResources(
-    [this.inspector.commands.resourceCommand.TYPES.DOCUMENT_EVENT],
+    [
+      this.inspector.commands.resourceCommand.TYPES.DOCUMENT_EVENT,
+      this.inspector.commands.resourceCommand.TYPES.STYLESHEET,
+    ],
     {
       onAvailable: this._onResourceAvailable,
       ignoreExistingResources: true,
@@ -2140,6 +2143,11 @@ RuleViewTool.prototype = {
   },
 
   _onResourceAvailable(resources) {
+    if (!this.inspector) {
+      return;
+    }
+
+    let hasNewStylesheet = false;
     for (const resource of resources) {
       if (
         resource.resourceType ===
@@ -2148,7 +2156,23 @@ RuleViewTool.prototype = {
         resource.targetFront.isTopLevel
       ) {
         this.clearUserProperties();
+        continue;
       }
+
+      if (
+        resource.resourceType ===
+          this.inspector.commands.resourceCommand.TYPES.STYLESHEET &&
+        // resource.isNew is only true when the stylesheet was added from DevTools,
+        // for example when adding a rule in the rule view. In such cases, we're already
+        // updating the rule view, so ignore those.
+        !resource.isNew
+      ) {
+        hasNewStylesheet = true;
+      }
+    }
+
+    if (hasNewStylesheet) {
+      this.refresh();
     }
   },
 
diff --git a/devtools/client/inspector/rules/test/browser_part2.ini b/devtools/client/inspector/rules/test/browser_part2.ini
index 04b08281cb8a..e7f32804d4ef 100644
--- a/devtools/client/inspector/rules/test/browser_part2.ini
+++ b/devtools/client/inspector/rules/test/browser_part2.ini
@@ -173,6 +173,7 @@ skip-if =
 [browser_rules_refresh-no-flicker.js]
 [browser_rules_refresh-on-attribute-change_01.js]
 [browser_rules_refresh-on-style-change.js]
+[browser_rules_refresh-on-stylesheet-change.js]
 [browser_rules_search-filter-computed-list_01.js]
 [browser_rules_search-filter-computed-list_02.js]
 [browser_rules_search-filter-computed-list_03.js]
diff --git a/devtools/client/inspector/rules/test/browser_rules_refresh-on-stylesheet-change.js b/devtools/client/inspector/rules/test/browser_rules_refresh-on-stylesheet-change.js
new file mode 100644
index 000000000000..f9624d357091
--- /dev/null
+++ b/devtools/client/inspector/rules/test/browser_rules_refresh-on-stylesheet-change.js
@@ -0,0 +1,65 @@
+/* Any copyright is dedicated to the Public Domain.
+ http://creativecommons.org/publicdomain/zero/1.0/ */
+
+"use strict";
+
+// Test that the rule view refreshes when a stylesheet is added or modified
+
+const TEST_URI = "<h1>Hello DevTools</h1>";
+
+add_task(async function () {
+  await addTab("data:text/html;charset=utf-8," + encodeURIComponent(TEST_URI));
+  const { inspector, view } = await openRuleView();
+
+  await selectNode("h1", inspector);
+
+  info("Add a stylesheet with matching rule for the h1 node");
+  let onUpdated = inspector.once("rule-view-refreshed");
+  await SpecialPowers.spawn(gBrowser.selectedBrowser, [], () => {
+    const addedStylesheet = content.document.createElement("style");
+    addedStylesheet.textContent = "h1 { background: tomato }";
+    content.document.head.append(addedStylesheet);
+  });
+  await onUpdated;
+  ok(true, "Rules view was refreshed when adding a stylesheet");
+  checkRulesViewSelectors(view, ["element", "h1"]);
+  is(
+    getRuleViewPropertyValue(view, "h1", "background"),
+    "tomato",
+    "Expected value is displayed for the background property"
+  );
+
+  info("Modify the stylesheet added previously");
+  onUpdated = inspector.once("rule-view-refreshed");
+  await SpecialPowers.spawn(gBrowser.selectedBrowser, [], () => {
+    const addedStylesheet = content.document.querySelector("style");
+    addedStylesheet.textContent = "body h1 { background: gold; color: navy; }";
+  });
+  await onUpdated;
+  ok(true, "Rules view was refreshed when updating the stylesheet");
+  checkRulesViewSelectors(view, ["element", "body h1"]);
+  is(
+    getRuleViewPropertyValue(view, "body h1", "background"),
+    "gold",
+    "Expected value is displayed for the background property"
+  );
+  is(
+    getRuleViewPropertyValue(view, "body h1", "color"),
+    "navy",
+    "Expected value is displayed for the color property"
+  );
+});
+
+function checkRulesViewSelectors(view, expectedSelectors) {
+  Assert.deepEqual(
+    getRuleSelectors(view),
+    expectedSelectors,
+    "Expected selectors are displayed"
+  );
+}
+
+function getRuleSelectors(view) {
+  return Array.from(
+    view.styleDocument.querySelectorAll(".ruleview-selectorcontainer")
+  ).map(el => el.textContent);
+}
diff --git a/devtools/client/inspector/rules/test/browser_rules_user-agent-styles.js b/devtools/client/inspector/rules/test/browser_rules_user-agent-styles.js
index 916a6e052614..8c4179bac08c 100644
--- a/devtools/client/inspector/rules/test/browser_rules_user-agent-styles.js
+++ b/devtools/client/inspector/rules/test/browser_rules_user-agent-styles.js
@@ -185,6 +185,7 @@ async function compareAppliedStylesWithUI(inspector, view, filter) {
   entries = [...entryMap.values()];
 
   const elementStyle = view._elementStyle;
+  await waitFor(() => elementStyle.rules.length === entries.length);
   is(
     elementStyle.rules.length,
     entries.length,
diff --git a/devtools/client/inspector/test/head.js b/devtools/client/inspector/test/head.js
index dc7145be5d27..ae2784b94b76 100644
--- a/devtools/client/inspector/test/head.js
+++ b/devtools/client/inspector/test/head.js
@@ -1008,9 +1008,14 @@ async function assertTooltipHiddenOnMouseOut(tooltip, target) {
  * @return {DOMNode} The rule editor if any at this index
  */
 function getRuleViewRuleEditor(view, childrenIndex, nodeIndex) {
+  const child = view.element.children[childrenIndex];
+  if (!child) {
+    return null;
+  }
+
   return nodeIndex !== undefined
-    ? view.element.children[childrenIndex].childNodes[nodeIndex]._ruleEditor
-    : view.element.children[childrenIndex]._ruleEditor;
+    ? child.childNodes[nodeIndex]?._ruleEditor
+    : child._ruleEditor;
 }
 
 /**