diff --git a/.changelog/26285.txt b/.changelog/26285.txt
new file mode 100644
index 000000000..841726c6f
--- /dev/null
+++ b/.changelog/26285.txt
@@ -0,0 +1,3 @@
+```release-note:bug
+jobspec: Validate required hook field in lifecycle block
+```
diff --git a/api/tasks.go b/api/tasks.go
index 3f3ea4f07..e6d77d830 100644
--- a/api/tasks.go
+++ b/api/tasks.go
@@ -747,13 +747,13 @@ const (
 )
 
 type TaskLifecycle struct {
-	Hook    string `mapstructure:"hook" hcl:"hook,optional"`
+	Hook    string `mapstructure:"hook" hcl:"hook"`
 	Sidecar bool   `mapstructure:"sidecar" hcl:"sidecar,optional"`
 }
 
 // Determine if lifecycle has user-input values
 func (l *TaskLifecycle) Empty() bool {
-	return l == nil || (l.Hook == "")
+	return l == nil
 }
 
 // Task is a single process in a task group.
diff --git a/api/tasks_test.go b/api/tasks_test.go
index 38f70c718..392dfc67a 100644
--- a/api/tasks_test.go
+++ b/api/tasks_test.go
@@ -344,10 +344,36 @@ func TestTask_Canonicalize_TaskLifecycle(t *testing.T) {
 		{
 			name: "empty",
 			task: &Task{
-				Lifecycle: &TaskLifecycle{},
+				Lifecycle: nil,
 			},
 			expected: nil,
 		},
+		{
+			name: "missing hook",
+			task: &Task{
+				Lifecycle: &TaskLifecycle{},
+			},
+			expected: &TaskLifecycle{},
+		},
+		{
+			name: "with sidecar",
+			task: &Task{
+				Lifecycle: &TaskLifecycle{
+					Sidecar: true,
+				},
+			},
+			expected: &TaskLifecycle{Sidecar: true},
+		},
+		{
+			name: "valid",
+			task: &Task{
+				Lifecycle: &TaskLifecycle{
+					Hook:    "prestart",
+					Sidecar: true,
+				},
+			},
+			expected: &TaskLifecycle{Hook: "prestart", Sidecar: true},
+		},
 	}
 
 	for _, tc := range testCases {