diff --git a/pkg/apis/core/validation/validation.go b/pkg/apis/core/validation/validation.go
index ec8045c0368..6af9e0797c5 100644
--- a/pkg/apis/core/validation/validation.go
+++ b/pkg/apis/core/validation/validation.go
@@ -2816,6 +2816,19 @@ func validatePodResourceClaimSource(claimSource core.ClaimSource, fldPath *field
 	return allErrs
 }
 
+func validateReadinessProbe(probe *core.Probe, fldPath *field.Path) field.ErrorList {
+	allErrs := field.ErrorList{}
+
+	if probe == nil {
+		return allErrs
+	}
+	allErrs = append(allErrs, validateProbe(probe, fldPath)...)
+	if probe.TerminationGracePeriodSeconds != nil {
+		allErrs = append(allErrs, field.Invalid(fldPath.Child("terminationGracePeriodSeconds"), probe.TerminationGracePeriodSeconds, "must not be set for readinessProbes"))
+	}
+	return allErrs
+}
+
 func validateStartupProbe(probe *core.Probe, fldPath *field.Path) field.ErrorList {
 	allErrs := field.ErrorList{}
 
@@ -3223,10 +3236,7 @@ func validateInitContainers(containers []core.Container, regularContainers []cor
 			if ctr.LivenessProbe != nil {
 				allErrs = append(allErrs, field.Forbidden(idxPath.Child("livenessProbe"), "may not be set for init containers"))
 			}
-			// TODO: Allow restartable init containers to have a readiness probe.
-			if ctr.ReadinessProbe != nil {
-				allErrs = append(allErrs, field.Forbidden(idxPath.Child("readinessProbe"), "may not be set for init containers"))
-			}
+			allErrs = append(allErrs, validateReadinessProbe(ctr.ReadinessProbe, idxPath.Child("readinessProbe"))...)
 			allErrs = append(allErrs, validateStartupProbe(ctr.StartupProbe, idxPath.Child("startupProbe"))...)
 
 		default:
@@ -3238,7 +3248,7 @@ func validateInitContainers(containers []core.Container, regularContainers []cor
 				allErrs = append(allErrs, field.Forbidden(idxPath.Child("livenessProbe"), "may not be set for init containers"))
 			}
 			if ctr.ReadinessProbe != nil {
-				allErrs = append(allErrs, field.Forbidden(idxPath.Child("readinessProbe"), "may not be set for init containers"))
+				allErrs = append(allErrs, field.Forbidden(idxPath.Child("readinessProbe"), "may not be set for init containers without restartPolicy=Always"))
 			}
 			if ctr.StartupProbe != nil {
 				allErrs = append(allErrs, field.Forbidden(idxPath.Child("startupProbe"), "may not be set for init containers without restartPolicy=Always"))
@@ -3359,10 +3369,7 @@ func validateContainers(containers []core.Container, volumes map[string]core.Vol
 		if ctr.LivenessProbe != nil && ctr.LivenessProbe.SuccessThreshold != 1 {
 			allErrs = append(allErrs, field.Invalid(path.Child("livenessProbe", "successThreshold"), ctr.LivenessProbe.SuccessThreshold, "must be 1"))
 		}
-		allErrs = append(allErrs, validateProbe(ctr.ReadinessProbe, path.Child("readinessProbe"))...)
-		if ctr.ReadinessProbe != nil && ctr.ReadinessProbe.TerminationGracePeriodSeconds != nil {
-			allErrs = append(allErrs, field.Invalid(path.Child("readinessProbe", "terminationGracePeriodSeconds"), ctr.ReadinessProbe.TerminationGracePeriodSeconds, "must not be set for readinessProbes"))
-		}
+		allErrs = append(allErrs, validateReadinessProbe(ctr.ReadinessProbe, path.Child("readinessProbe"))...)
 		allErrs = append(allErrs, validateStartupProbe(ctr.StartupProbe, path.Child("startupProbe"))...)
 
 		// These fields are disallowed for regular containers
diff --git a/pkg/apis/core/validation/validation_test.go b/pkg/apis/core/validation/validation_test.go
index 951384547cd..17610b0045a 100644
--- a/pkg/apis/core/validation/validation_test.go
+++ b/pkg/apis/core/validation/validation_test.go
@@ -8164,11 +8164,18 @@ func TestValidateInitContainers(t *testing.T) {
 		ImagePullPolicy:          "IfNotPresent",
 		TerminationMessagePolicy: "File",
 	}, {
-		Name:                     "container-3-restart-always-with-startup-probe",
+		Name:                     "container-3-restart-always-with-probes",
 		Image:                    "image",
 		ImagePullPolicy:          "IfNotPresent",
 		TerminationMessagePolicy: "File",
 		RestartPolicy:            &containerRestartPolicyAlways,
+		ReadinessProbe: &core.Probe{
+			ProbeHandler: core.ProbeHandler{
+				TCPSocket: &core.TCPSocketAction{
+					Port: intstr.FromInt32(80),
+				},
+			},
+		},
 		StartupProbe: &core.Probe{
 			ProbeHandler: core.ProbeHandler{
 				TCPSocket: &core.TCPSocketAction{Port: intstr.FromInt(80)},
@@ -8392,6 +8399,25 @@ func TestValidateInitContainers(t *testing.T) {
 			},
 		}},
 		field.ErrorList{{Type: field.ErrorTypeInvalid, Field: "initContainers[0].startupProbe.successThreshold", BadValue: int32(2)}},
+	}, {
+		"invalid readiness probe, terminationGracePeriodSeconds set.",
+		line(),
+		[]core.Container{{
+			Name:                     "life-123",
+			Image:                    "image",
+			ImagePullPolicy:          "IfNotPresent",
+			TerminationMessagePolicy: "File",
+			RestartPolicy:            &containerRestartPolicyAlways,
+			ReadinessProbe: &core.Probe{
+				ProbeHandler: core.ProbeHandler{
+					TCPSocket: &core.TCPSocketAction{
+						Port: intstr.FromInt32(80),
+					},
+				},
+				TerminationGracePeriodSeconds: utilpointer.Int64(10),
+			},
+		}},
+		field.ErrorList{{Type: field.ErrorTypeInvalid, Field: "initContainers[0].readinessProbe.terminationGracePeriodSeconds", BadValue: utilpointer.Int64(10)}},
 	},
 	}
 	for _, tc := range errorCases {
diff --git a/pkg/kubelet/prober/prober_manager_test.go b/pkg/kubelet/prober/prober_manager_test.go
index 29d5551c443..9c8badbab52 100644
--- a/pkg/kubelet/prober/prober_manager_test.go
+++ b/pkg/kubelet/prober/prober_manager_test.go
@@ -152,8 +152,11 @@ func TestAddRemovePodsWithRestartableInitContainer(t *testing.T) {
 			enableSidecarContainers: false,
 		},
 		{
-			desc:                    "pod with sidecar (sidecar containers feature enabled)",
-			probePaths:              []probeKey{{"restartable_init_container_pod", "restartable-init", readiness}},
+			desc: "pod with sidecar (sidecar containers feature enabled)",
+			probePaths: []probeKey{
+				{"restartable_init_container_pod", "restartable-init", readiness},
+				{"restartable_init_container_pod", "restartable-init", startup},
+			},
 			enableSidecarContainers: true,
 		},
 	}
@@ -180,6 +183,7 @@ func TestAddRemovePodsWithRestartableInitContainer(t *testing.T) {
 					}, {
 						Name:           "restartable-init",
 						ReadinessProbe: defaultProbe,
+						StartupProbe:   defaultProbe,
 						RestartPolicy:  containerRestartPolicy(tc.enableSidecarContainers),
 					}},
 					Containers: []v1.Container{{