diff --git a/common/changes/@microsoft/rush/cobuild-telemetry-skew_2024-05-30-20-57.json b/common/changes/@microsoft/rush/cobuild-telemetry-skew_2024-05-30-20-57.json
new file mode 100644
index 00000000000..a01b63f97bc
--- /dev/null
+++ b/common/changes/@microsoft/rush/cobuild-telemetry-skew_2024-05-30-20-57.json
@@ -0,0 +1,10 @@
+{
+  "changes": [
+    {
+      "packageName": "@microsoft/rush",
+      "comment": "Adds a new `wasExecutedOnThisMachine` property to operation telemetry events, to simplify reporting about cobuilt operations.",
+      "type": "none"
+    }
+  ],
+  "packageName": "@microsoft/rush"
+}
\ No newline at end of file
diff --git a/common/reviews/api/rush-lib.api.md b/common/reviews/api/rush-lib.api.md
index fb531f2d946..454ac3daa07 100644
--- a/common/reviews/api/rush-lib.api.md
+++ b/common/reviews/api/rush-lib.api.md
@@ -885,6 +885,7 @@ export interface ITelemetryOperationResult {
     nonCachedDurationMs?: number;
     result: string;
     startTimestampMs?: number;
+    wasExecutedOnThisMachine?: boolean;
 }
 
 // @public
diff --git a/libraries/rush-lib/src/cli/scriptActions/PhasedScriptAction.ts b/libraries/rush-lib/src/cli/scriptActions/PhasedScriptAction.ts
index c70ded04928..6eed33d9d00 100644
--- a/libraries/rush-lib/src/cli/scriptActions/PhasedScriptAction.ts
+++ b/libraries/rush-lib/src/cli/scriptActions/PhasedScriptAction.ts
@@ -804,7 +804,7 @@ export class PhasedScriptAction extends BaseScriptAction<IPhasedCommandConfig> {
       executionManagerOptions
     );
 
-    const { isInitial, isWatch } = options.executeOperationsContext;
+    const { isInitial, isWatch, cobuildConfiguration } = options.executeOperationsContext;
 
     let success: boolean = false;
     let result: IExecutionResult | undefined;
@@ -902,6 +902,9 @@ export class PhasedScriptAction extends BaseScriptAction<IPhasedCommandConfig> {
             startTimestampMs: startTime,
             endTimestampMs: endTime,
             nonCachedDurationMs: operationResult.nonCachedDurationMs,
+            wasExecutedOnThisMachine:
+              !operationResult.cobuildRunnerId ||
+              operationResult.cobuildRunnerId === cobuildConfiguration?.cobuildRunnerId,
             result: operationResult.status,
             dependencies: Array.from(getNonSilentDependencies(operation)).sort()
           };
diff --git a/libraries/rush-lib/src/logic/Telemetry.ts b/libraries/rush-lib/src/logic/Telemetry.ts
index 761638499a6..76b94020abe 100644
--- a/libraries/rush-lib/src/logic/Telemetry.ts
+++ b/libraries/rush-lib/src/logic/Telemetry.ts
@@ -71,6 +71,12 @@ export interface ITelemetryOperationResult {
    * Duration in milliseconds when the operation does not hit cache
    */
   nonCachedDurationMs?: number;
+
+  /**
+   * Was this operation built on this machine? If so, the duration can be calculated from `startTimestampMs` and `endTimestampMs`.
+   *  If not, you should use the metrics from the machine that built it.
+   */
+  wasExecutedOnThisMachine?: boolean;
 }
 
 /**