diff --git a/core/services/workflows/v2/engine_execution_concurrency_test.go b/core/services/workflows/v2/engine_execution_concurrency_test.go
new file mode 100644
index 00000000000..0123d59ecc0
--- /dev/null
+++ b/core/services/workflows/v2/engine_execution_concurrency_test.go
@@ -0,0 +1,147 @@
+package v2_test
+
+import (
+	"context"
+	"runtime"
+	"slices"
+	"sync"
+	"testing"
+	"time"
+
+	"github.com/stretchr/testify/mock"
+	"github.com/stretchr/testify/require"
+
+	"github.com/smartcontractkit/chainlink-common/pkg/capabilities"
+	"github.com/smartcontractkit/chainlink-common/pkg/settings/cresettings"
+	modulemocks "github.com/smartcontractkit/chainlink-common/pkg/workflows/wasm/host/mocks"
+	sdkpb "github.com/smartcontractkit/chainlink-protos/cre/go/sdk"
+
+	regmocks "github.com/smartcontractkit/chainlink-common/pkg/types/core/mocks"
+
+	"github.com/smartcontractkit/chainlink-common/pkg/workflows/wasm/host"
+	capmocks "github.com/smartcontractkit/chainlink/v2/core/capabilities/mocks"
+	workflowEvents "github.com/smartcontractkit/chainlink/v2/core/services/workflows/events"
+	v2 "github.com/smartcontractkit/chainlink/v2/core/services/workflows/v2"
+	"github.com/smartcontractkit/chainlink/v2/core/utils/matches"
+)
+
+// TestEngine_ExecutionConcurrencySerializesOverlappingRuns proves that when PerWorkflow
+// ExecutionConcurrencyLimit is 1, a second trigger cannot start Module.Execute until the first
+// run completes (executionsSemaphore.Wait blocks in handleAllTriggerEvents).
+func TestEngine_ExecutionConcurrencySerializesOverlappingRuns(t *testing.T) {
+	t.Parallel()
+
+	continueFirst := make(chan struct{})
+	var execMu sync.Mutex
+	var execOrder []string
+
+	module := modulemocks.NewModuleV2(t)
+	module.EXPECT().Start().Once()
+	module.EXPECT().Execute(matches.AnyContext, mock.Anything, mock.Anything).Return(newTriggerSubs(1), nil).Once()
+	module.EXPECT().Execute(matches.AnyContext, mock.Anything, mock.Anything).Run(
+		func(_ context.Context, _ *sdkpb.ExecuteRequest, eh host.ExecutionHelper) {
+			execMu.Lock()
+			execOrder = append(execOrder, eh.GetWorkflowExecutionID())
+			n := len(execOrder)
+			execMu.Unlock()
+			if n == 1 {
+				<-continueFirst
+			}
+		}).Return(nil, nil).Times(2)
+	module.EXPECT().Close().Once()
+
+	capreg := regmocks.NewCapabilitiesRegistry(t)
+	capreg.EXPECT().LocalNode(matches.AnyContext).Return(newNode(t), nil).Once()
+
+	initDoneCh := make(chan error, 1)
+	subscribedToTriggersCh := make(chan []string, 1)
+	executionFinishedCh := make(chan string, 2)
+
+	cfg := defaultTestConfig(t, func(cfg *cresettings.Workflows) {
+		cfg.ExecutionConcurrencyLimit.DefaultValue = 1
+	})
+	cfg.Module = module
+	cfg.CapRegistry = capreg
+	cfg.BillingClient = setupMockBillingClient(t)
+
+	wantExecID1, err := workflowEvents.GenerateExecutionID(cfg.WorkflowID, "event_concurrency_1")
+	require.NoError(t, err)
+	wantExecID2, err := workflowEvents.GenerateExecutionID(cfg.WorkflowID, "event_concurrency_2")
+	require.NoError(t, err)
+
+	cfg.Hooks = v2.LifecycleHooks{
+		OnInitialized: func(err error) {
+			initDoneCh <- err
+		},
+		OnSubscribedToTriggers: func(triggerIDs []string) {
+			subscribedToTriggersCh <- triggerIDs
+		},
+		OnExecutionFinished: func(executionID string, _ string) {
+			executionFinishedCh <- executionID
+			if executionID == wantExecID2 {
+				close(executionFinishedCh)
+			}
+		},
+	}
+
+	engine, err := v2.NewEngine(cfg)
+	require.NoError(t, err)
+
+	trigger := capmocks.NewTriggerCapability(t)
+	capreg.EXPECT().GetTrigger(matches.AnyContext, "id_0").Return(trigger, nil).Once()
+	eventCh := make(chan capabilities.TriggerResponse)
+	trigger.EXPECT().RegisterTrigger(matches.AnyContext, mock.Anything).Return(eventCh, nil).Once()
+	trigger.EXPECT().UnregisterTrigger(matches.AnyContext, mock.Anything).Return(nil).Once()
+	trigger.EXPECT().AckEvent(matches.AnyContext, mock.Anything, mock.Anything, mock.Anything).Return(nil).Maybe()
+
+	require.NoError(t, engine.Start(t.Context()))
+	require.NoError(t, <-initDoneCh)
+	require.Equal(t, []string{"id_0"}, <-subscribedToTriggersCh)
+
+	eventCh <- capabilities.TriggerResponse{
+		Event: capabilities.TriggerEvent{
+			TriggerType: "basic-trigger@1.0.0",
+			ID:          "event_concurrency_1",
+			Payload:     nil,
+		},
+	}
+
+	require.Eventually(t, func() bool {
+		execMu.Lock()
+		defer execMu.Unlock()
+		return len(execOrder) == 1 && execOrder[0] == wantExecID1
+	}, 2*time.Second, 5*time.Millisecond, "first execution should start")
+
+	eventCh <- capabilities.TriggerResponse{
+		Event: capabilities.TriggerEvent{
+			TriggerType: "basic-trigger@1.0.0",
+			ID:          "event_concurrency_2",
+			Payload:     nil,
+		},
+	}
+
+	for i := 0; i < 10_000; i++ {
+		runtime.Gosched()
+	}
+	execMu.Lock()
+	gotMid := slices.Clone(execOrder)
+	execMu.Unlock()
+	require.Equal(t, []string{wantExecID1}, gotMid,
+		"second execution must not start while the first holds the executions semaphore")
+
+	continueFirst <- struct{}{}
+
+	require.Eventually(t, func() bool {
+		execMu.Lock()
+		defer execMu.Unlock()
+		return slices.Equal(execOrder, []string{wantExecID1, wantExecID2})
+	}, 2*time.Second, 5*time.Millisecond, "second execution should start after the first completes")
+
+	finishedIDs := make([]string, 0, 2)
+	for id := range executionFinishedCh {
+		finishedIDs = append(finishedIDs, id)
+	}
+	require.Equal(t, []string{wantExecID1, wantExecID2}, finishedIDs)
+
+	require.NoError(t, engine.Close())
+}