diff --git a/spec/unit/pushprocessor.spec.ts b/spec/unit/pushprocessor.spec.ts
index 2f219b307..141e34445 100644
--- a/spec/unit/pushprocessor.spec.ts
+++ b/spec/unit/pushprocessor.spec.ts
@@ -1,6 +1,6 @@
 import * as utils from "../test-utils/test-utils";
 import { IActionsObject, PushProcessor } from "../../src/pushprocessor";
-import { ConditionKind, EventType, IContent, MatrixClient, MatrixEvent, PushRuleActionName } from "../../src";
+import { ConditionKind, EventType, IContent, MatrixClient, MatrixEvent, PushRuleActionName, RuleId } from "../../src";
 
 describe("NotificationService", function () {
     const testUserId = "@ali:matrix.org";
@@ -48,6 +48,7 @@ describe("NotificationService", function () {
         credentials: {
             userId: testUserId,
         },
+        supportsIntentionalMentions: () => true,
         pushRules: {
             device: {},
             global: {
@@ -712,6 +713,37 @@ describe("NotificationService", function () {
             });
         });
     });
+
+    describe("test intentional mentions behaviour", () => {
+        it.each([RuleId.ContainsUserName, RuleId.ContainsDisplayName, RuleId.AtRoomNotification])(
+            "Rule %s matches unless intentional mentions are enabled",
+            (ruleId) => {
+                const rule = {
+                    rule_id: ruleId,
+                    actions: [],
+                    conditions: [],
+                    default: false,
+                    enabled: true,
+                };
+                expect(pushProcessor.ruleMatchesEvent(rule, testEvent)).toBe(true);
+
+                // Add the mentions property to the event and the rule is now disabled.
+                testEvent = utils.mkEvent({
+                    type: "m.room.message",
+                    room: testRoomId,
+                    user: "@alfred:localhost",
+                    event: true,
+                    content: {
+                        "body": "",
+                        "msgtype": "m.text",
+                        "org.matrix.msc3952.mentions": {},
+                    },
+                });
+
+                expect(pushProcessor.ruleMatchesEvent(rule, testEvent)).toBe(false);
+            },
+        );
+    });
 });
 
 describe("Test PushProcessor.partsForDottedKey", function () {
diff --git a/src/@types/PushRules.ts b/src/@types/PushRules.ts
index 2234a62c2..da3b01b6d 100644
--- a/src/@types/PushRules.ts
+++ b/src/@types/PushRules.ts
@@ -137,6 +137,8 @@ export enum PushRuleKind {
 
 export enum RuleId {
     Master = ".m.rule.master",
+    IsUserMention = ".org.matrix.msc3952.is_user_mention",
+    IsRoomMention = ".org.matrix.msc3952.is_room_mention",
     ContainsDisplayName = ".m.rule.contains_display_name",
     ContainsUserName = ".m.rule.contains_user_name",
     AtRoomNotification = ".m.rule.roomnotif",
diff --git a/src/client.ts b/src/client.ts
index 132be9550..ef2517a44 100644
--- a/src/client.ts
+++ b/src/client.ts
@@ -461,6 +461,11 @@ export interface IStartClientOpts {
      * @experimental
      */
     slidingSync?: SlidingSync;
+
+    /**
+     * @experimental
+     */
+    intentionalMentions?: boolean;
 }
 
 export interface IStoredClientOpts extends IStartClientOpts {}
@@ -8575,7 +8580,7 @@ export class MatrixClient extends TypedEventEmitter<EmittedEvents, ClientEventHa
      */
     public setPushRules(rules: IPushRules): void {
         // Fix-up defaults, if applicable.
-        this.pushRules = PushProcessor.rewriteDefaultRules(rules);
+        this.pushRules = PushProcessor.rewriteDefaultRules(rules, this.getUserId()!);
         // Pre-calculate any necessary caches.
         this.pushProcessor.updateCachedPushRuleKeys(this.pushRules);
     }
@@ -9472,6 +9477,15 @@ export class MatrixClient extends TypedEventEmitter<EmittedEvents, ClientEventHa
         return this.clientOpts?.threadSupport || false;
     }
 
+    /**
+     * A helper to determine intentional mentions support
+     * @returns a boolean to determine if intentional mentions are enabled
+     * @experimental
+     */
+    public supportsIntentionalMentions(): boolean {
+        return this.clientOpts?.intentionalMentions || false;
+    }
+
     /**
      * Fetches the summary of a room as defined by an initial version of MSC3266 and implemented in Synapse
      * Proposed at https://github.com/matrix-org/matrix-doc/pull/3266
diff --git a/src/models/event.ts b/src/models/event.ts
index 0ad2b5c18..2db3479cd 100644
--- a/src/models/event.ts
+++ b/src/models/event.ts
@@ -48,6 +48,8 @@ export interface IContent {
     "avatar_url"?: string;
     "displayname"?: string;
     "m.relates_to"?: IEventRelation;
+
+    "org.matrix.msc3952.mentions"?: IMentions;
 }
 
 type StrippedState = Required<Pick<IEvent, "content" | "state_key" | "type" | "sender">>;
@@ -114,6 +116,11 @@ export interface IEventRelation {
     "key"?: string;
 }
 
+export interface IMentions {
+    user_ids?: string[];
+    room?: boolean;
+}
+
 /**
  * When an event is a visibility change event, as per MSC3531,
  * the visibility change implied by the event.
diff --git a/src/pushprocessor.ts b/src/pushprocessor.ts
index 46546e3c6..78d26fe5a 100644
--- a/src/pushprocessor.ts
+++ b/src/pushprocessor.ts
@@ -36,6 +36,7 @@ import {
     PushRuleCondition,
     PushRuleKind,
     PushRuleSet,
+    RuleId,
     TweakName,
 } from "./@types/PushRules";
 import { EventType } from "./@types/event";
@@ -70,6 +71,36 @@ const DEFAULT_OVERRIDE_RULES: IPushRule[] = [
         ],
         actions: [PushRuleActionName.DontNotify],
     },
+    {
+        rule_id: RuleId.IsUserMention,
+        default: true,
+        enabled: true,
+        conditions: [
+            {
+                kind: ConditionKind.EventPropertyContains,
+                key: "content.org\\.matrix\\.msc3952\\.mentions.user_ids",
+                value: "", // The user ID is dynamically added in rewriteDefaultRules.
+            },
+        ],
+        actions: [PushRuleActionName.Notify, { set_tweak: TweakName.Highlight }],
+    },
+    {
+        rule_id: RuleId.IsRoomMention,
+        default: true,
+        enabled: true,
+        conditions: [
+            {
+                kind: ConditionKind.EventPropertyIs,
+                key: "content.org\\.matrix\\.msc3952\\.mentions.room",
+                value: true,
+            },
+            {
+                kind: ConditionKind.SenderNotificationPermission,
+                key: "room",
+            },
+        ],
+        actions: [PushRuleActionName.Notify, { set_tweak: TweakName.Highlight }],
+    },
     {
         // For homeservers which don't support MSC3786 yet
         rule_id: ".org.matrix.msc3786.rule.room.server_acl",
@@ -160,9 +191,10 @@ export class PushProcessor {
      * where applicable. Useful for upgrading push rules to more strict
      * conditions when the server is falling behind on defaults.
      * @param incomingRules - The client's existing push rules
+     * @param userId - The Matrix ID of the client.
      * @returns The rewritten rules
      */
-    public static rewriteDefaultRules(incomingRules: IPushRules): IPushRules {
+    public static rewriteDefaultRules(incomingRules: IPushRules, userId: string | undefined = undefined): IPushRules {
         let newRules: IPushRules = JSON.parse(JSON.stringify(incomingRules)); // deep clone
 
         // These lines are mostly to make the tests happy. We shouldn't run into these
@@ -174,8 +206,22 @@ export class PushProcessor {
 
         // Merge the client-level defaults with the ones from the server
         const globalOverrides = newRules.global.override;
-        for (const override of DEFAULT_OVERRIDE_RULES) {
-            const existingRule = globalOverrides.find((r) => r.rule_id === override.rule_id);
+        for (const originalOverride of DEFAULT_OVERRIDE_RULES) {
+            const existingRule = globalOverrides.find((r) => r.rule_id === originalOverride.rule_id);
+
+            // Dynamically add the user ID as the value for the is_user_mention rule.
+            let override: IPushRule;
+            if (originalOverride.rule_id === RuleId.IsUserMention) {
+                // If the user ID wasn't provided, skip the rule.
+                if (!userId) {
+                    continue;
+                }
+
+                override = JSON.parse(JSON.stringify(originalOverride)); // deep clone
+                override.conditions![0].value = userId;
+            } else {
+                override = originalOverride;
+            }
 
             if (existingRule) {
                 // Copy over the actions, default, and conditions. Don't touch the user's preference.
@@ -668,6 +714,17 @@ export class PushProcessor {
     }
 
     public ruleMatchesEvent(rule: Partial<IPushRule> & Pick<IPushRule, "conditions">, ev: MatrixEvent): boolean {
+        // Disable the deprecated mentions push rules if the new mentions property exists.
+        if (
+            this.client.supportsIntentionalMentions() &&
+            ev.getContent()["org.matrix.msc3952.mentions"] !== undefined &&
+            (rule.rule_id === RuleId.ContainsUserName ||
+                rule.rule_id === RuleId.ContainsDisplayName ||
+                rule.rule_id === RuleId.AtRoomNotification)
+        ) {
+            return false;
+        }
+
         return !rule.conditions?.some((cond) => !this.eventFulfillsCondition(cond, ev));
     }