diff --git a/x-pack/plugins/infra/server/lib/alerting/metric_threshold/metric_threshold_executor.ts b/x-pack/plugins/infra/server/lib/alerting/metric_threshold/metric_threshold_executor.ts
index a282a742d614..00a1d97dec81 100644
--- a/x-pack/plugins/infra/server/lib/alerting/metric_threshold/metric_threshold_executor.ts
+++ b/x-pack/plugins/infra/server/lib/alerting/metric_threshold/metric_threshold_executor.ts
@@ -5,6 +5,7 @@
  */
 import { mapValues, first } from 'lodash';
 import { i18n } from '@kbn/i18n';
+import moment from 'moment';
 import { InfraDatabaseSearchResponse } from '../../adapters/framework/adapter_types';
 import { createAfterKeyHandler } from '../../../utils/create_afterkey_handler';
 import { getAllCompositeData } from '../../../utils/get_all_composite_data';
@@ -336,6 +337,7 @@ export const createMetricThresholdExecutor = (libs: InfraBackendLibs, alertId: s
           group,
           alertState: stateToAlertMessage[nextState],
           reason,
+          timestamp: moment().toISOString(),
           value: mapToConditionsLookup(alertResults, (result) => result[group].currentValue),
           threshold: mapToConditionsLookup(criteria, (c) => c.threshold),
           metric: mapToConditionsLookup(criteria, (c) => c.metric),
diff --git a/x-pack/plugins/infra/server/lib/alerting/metric_threshold/register_metric_threshold_alert_type.ts b/x-pack/plugins/infra/server/lib/alerting/metric_threshold/register_metric_threshold_alert_type.ts
index 2c98a568d16d..02d9ca3e5f0c 100644
--- a/x-pack/plugins/infra/server/lib/alerting/metric_threshold/register_metric_threshold_alert_type.ts
+++ b/x-pack/plugins/infra/server/lib/alerting/metric_threshold/register_metric_threshold_alert_type.ts
@@ -55,6 +55,13 @@ export function registerMetricThresholdAlertType(libs: InfraBackendLibs) {
     }
   );
 
+  const timestampActionVariableDescription = i18n.translate(
+    'xpack.infra.metrics.alerting.threshold.alerting.timestampDescription',
+    {
+      defaultMessage: 'A timestamp of when the alert was detected.',
+    }
+  );
+
   const valueActionVariableDescription = i18n.translate(
     'xpack.infra.metrics.alerting.threshold.alerting.valueActionVariableDescription',
     {
@@ -106,6 +113,7 @@ export function registerMetricThresholdAlertType(libs: InfraBackendLibs) {
         { name: 'group', description: groupActionVariableDescription },
         { name: 'alertState', description: alertStateActionVariableDescription },
         { name: 'reason', description: reasonActionVariableDescription },
+        { name: 'timestamp', description: timestampActionVariableDescription },
         { name: 'value', description: valueActionVariableDescription },
         { name: 'metric', description: metricActionVariableDescription },
         { name: 'threshold', description: thresholdActionVariableDescription },