diff --git a/internal/handlers/app.go b/internal/handlers/app.go
index 596337d..ccdaf14 100644
--- a/internal/handlers/app.go
+++ b/internal/handlers/app.go
@@ -345,10 +345,12 @@ func (h *Handlers) HandleAppDeploy() http.HandlerFunc {
 			}
 		}(deployCtx, application)
 
+		redirectURL := "/apps/" + application.ID + "/deployments"
+
 		http.Redirect(
 			writer,
 			request,
-			"/apps/"+application.ID+"/deployments",
+			redirectURL,
 			http.StatusSeeOther,
 		)
 	}
diff --git a/internal/service/deploy/cancel_test.go b/internal/service/deploy/cancel_test.go
new file mode 100644
index 0000000..f52ed92
--- /dev/null
+++ b/internal/service/deploy/cancel_test.go
@@ -0,0 +1,172 @@
+package deploy_test
+
+import (
+	"context"
+	"errors"
+	"sync"
+	"testing"
+	"time"
+
+	"github.com/stretchr/testify/assert"
+	"github.com/stretchr/testify/require"
+	"go.uber.org/fx"
+
+	"git.eeqj.de/sneak/upaas/internal/config"
+	"git.eeqj.de/sneak/upaas/internal/database"
+	"git.eeqj.de/sneak/upaas/internal/docker"
+	"git.eeqj.de/sneak/upaas/internal/globals"
+	"git.eeqj.de/sneak/upaas/internal/logger"
+	"git.eeqj.de/sneak/upaas/internal/models"
+	"git.eeqj.de/sneak/upaas/internal/service/deploy"
+	"git.eeqj.de/sneak/upaas/internal/service/notify"
+)
+
+func setupDeployService(t *testing.T) (*deploy.Service, *database.Database) {
+	t.Helper()
+
+	tmpDir := t.TempDir()
+
+	globals.SetAppname("upaas-test")
+	globals.SetVersion("test")
+
+	globalsInst, err := globals.New(fx.Lifecycle(nil))
+	require.NoError(t, err)
+
+	loggerInst, err := logger.New(fx.Lifecycle(nil), logger.Params{Globals: globalsInst})
+	require.NoError(t, err)
+
+	cfg := &config.Config{Port: 8080, DataDir: tmpDir, SessionSecret: "test-secret-key-at-least-32-chars"}
+
+	dbInst, err := database.New(fx.Lifecycle(nil), database.Params{Logger: loggerInst, Config: cfg})
+	require.NoError(t, err)
+
+	dockerClient, err := docker.New(fx.Lifecycle(nil), docker.Params{Logger: loggerInst, Config: cfg})
+	require.NoError(t, err)
+
+	notifySvc, err := notify.New(fx.Lifecycle(nil), notify.ServiceParams{Logger: loggerInst})
+	require.NoError(t, err)
+
+	svc, err := deploy.New(fx.Lifecycle(nil), deploy.ServiceParams{
+		Logger: loggerInst, Config: cfg, Database: dbInst, Docker: dockerClient, Notify: notifySvc,
+	})
+	require.NoError(t, err)
+
+	return svc, dbInst
+}
+
+func createDeployTestApp(t *testing.T, dbInst *database.Database) *models.App {
+	t.Helper()
+
+	app := models.NewApp(dbInst)
+	app.ID = "test-cancel-app"
+	app.Name = "test-cancel-app"
+	app.RepoURL = "git@example.com:user/repo.git"
+	app.Branch = "main"
+	app.DockerfilePath = "Dockerfile"
+	app.SSHPrivateKey = "private-key"
+	app.SSHPublicKey = "public-key"
+	app.Status = models.AppStatusPending
+
+	err := app.Save(context.Background())
+	require.NoError(t, err)
+
+	return app
+}
+
+func TestConcurrentDeploysOnSameApp(t *testing.T) {
+	t.Parallel()
+
+	svc, dbInst := setupDeployService(t)
+	app := createDeployTestApp(t, dbInst)
+
+	// Run two deploys concurrently - both will fail (no docker) but we verify
+	// the lock mechanism works (no panics, no data races)
+	var wg sync.WaitGroup
+
+	results := make([]error, 2)
+
+	for i := range 2 {
+		wg.Add(1)
+
+		go func(idx int) {
+			defer wg.Done()
+
+			results[idx] = svc.Deploy(context.Background(), app, nil)
+		}(i)
+	}
+
+	wg.Wait()
+
+	// At least one should have run (and failed due to docker not connected)
+	// The other either ran too or got ErrDeploymentInProgress
+	gotInProgress := false
+	gotOther := false
+
+	for _, err := range results {
+		require.Error(t, err)
+
+		if errors.Is(err, deploy.ErrDeploymentInProgress) {
+			gotInProgress = true
+		} else {
+			gotOther = true
+		}
+	}
+
+	// At least one must have actually attempted the deploy
+	assert.True(t, gotOther, "at least one deploy should have attempted execution")
+
+	// If timing worked out, one should have been rejected
+	// (but this is racy - both might complete sequentially)
+	_ = gotInProgress
+}
+
+func TestCancelAppDeployReturnsFalseWhenNoDeploy(t *testing.T) {
+	t.Parallel()
+
+	svc, _ := setupDeployService(t)
+
+	// No deploy in progress, should return false
+	cancelled := svc.CancelAppDeploy("nonexistent-app")
+	assert.False(t, cancelled)
+}
+
+func TestCancelAppDeployCancelsInProgressDeploy(t *testing.T) {
+	t.Parallel()
+
+	svc, dbInst := setupDeployService(t)
+	app := createDeployTestApp(t, dbInst)
+
+	deployStarted := make(chan struct{})
+	deployDone := make(chan error, 1)
+
+	// Start a deploy that will hold the lock
+	go func() {
+		// Signal when deploy starts (will acquire lock quickly)
+		close(deployStarted)
+
+		deployDone <- svc.Deploy(context.Background(), app, nil)
+	}()
+
+	<-deployStarted
+	// Give it time to acquire the lock and register the cancel func
+	time.Sleep(100 * time.Millisecond)
+
+	// Cancel should work if deploy is still in progress
+	_ = svc.CancelAppDeploy(app.ID)
+
+	// Wait for deploy to finish
+	select {
+	case <-deployDone:
+		// Deploy finished (either cancelled or failed for other reason)
+	case <-time.After(5 * time.Second):
+		t.Fatal("deploy did not finish after cancellation")
+	}
+}
+
+func TestErrDeployCancelledExists(t *testing.T) {
+	t.Parallel()
+
+	// Verify the sentinel error exists
+	require.Error(t, deploy.ErrDeployCancelled)
+	assert.Equal(t, "deployment cancelled by newer deploy", deploy.ErrDeployCancelled.Error())
+}
diff --git a/internal/service/deploy/deploy.go b/internal/service/deploy/deploy.go
index b51e15a..34dacd0 100644
--- a/internal/service/deploy/deploy.go
+++ b/internal/service/deploy/deploy.go
@@ -47,6 +47,8 @@ var (
 	ErrBuildTimeout = errors.New("build timeout exceeded")
 	// ErrDeployTimeout indicates the deploy phase exceeded the timeout.
 	ErrDeployTimeout = errors.New("deploy timeout exceeded")
+	// ErrDeployCancelled indicates the deployment was cancelled by a newer deploy.
+	ErrDeployCancelled = errors.New("deployment cancelled by newer deploy")
 )
 
 // logFlushInterval is how often to flush buffered logs to the database.
@@ -212,8 +214,9 @@ type Service struct {
 	docker   *docker.Client
 	notify   *notify.Service
 	config   *config.Config
-	params   *ServiceParams
-	appLocks sync.Map // map[string]*sync.Mutex - per-app deployment locks
+	params     *ServiceParams
+	appLocks   sync.Map // map[string]*sync.Mutex - per-app deployment locks
+	appCancels sync.Map // map[string]context.CancelFunc - per-app deploy cancellation
 }
 
 // New creates a new deploy Service.
@@ -274,6 +277,21 @@ func (svc *Service) GetLogFilePath(app *models.App, deployment *models.Deploymen
 	return filepath.Join(svc.config.DataDir, "logs", hostname, app.Name, filename)
 }
 
+// CancelAppDeploy cancels any in-progress deployment for the given app.
+// It returns true if a deployment was cancelled, false if none was in progress.
+func (svc *Service) CancelAppDeploy(appID string) bool {
+	if cancelVal, ok := svc.appCancels.Load(appID); ok {
+		if cancelFn, ok := cancelVal.(context.CancelFunc); ok {
+			svc.log.Info("cancelling in-progress deployment", "app_id", appID)
+			cancelFn()
+
+			return true
+		}
+	}
+
+	return false
+}
+
 // Deploy deploys an app.
 func (svc *Service) Deploy(
 	ctx context.Context,
@@ -288,6 +306,14 @@ func (svc *Service) Deploy(
 	}
 	defer svc.unlockApp(app.ID)
 
+	// Create a cancellable context so in-progress deploys can be cancelled
+	ctx, cancel := context.WithCancel(ctx)
+	defer cancel()
+
+	// Store the cancel func so other deploys can cancel this one
+	svc.appCancels.Store(app.ID, cancel)
+	defer svc.appCancels.Delete(app.ID)
+
 	// Fetch webhook event and create deployment record
 	webhookEvent := svc.fetchWebhookEvent(ctx, webhookEventID)
 
@@ -349,6 +375,13 @@ func (svc *Service) buildImageWithTimeout(
 			return "", timeoutErr
 		}
 
+		if errors.Is(ctx.Err(), context.Canceled) {
+			cancelErr := fmt.Errorf("%w", ErrDeployCancelled)
+			svc.failDeployment(context.WithoutCancel(ctx), app, deployment, cancelErr)
+
+			return "", cancelErr
+		}
+
 		return "", err
 	}
 
@@ -384,6 +417,13 @@ func (svc *Service) deployContainerWithTimeout(
 			return timeoutErr
 		}
 
+		if errors.Is(ctx.Err(), context.Canceled) {
+			cancelErr := fmt.Errorf("%w", ErrDeployCancelled)
+			svc.failDeployment(context.WithoutCancel(ctx), app, deployment, cancelErr)
+
+			return cancelErr
+		}
+
 		return err
 	}
 
diff --git a/internal/service/webhook/webhook.go b/internal/service/webhook/webhook.go
index 9687192..b0008fb 100644
--- a/internal/service/webhook/webhook.go
+++ b/internal/service/webhook/webhook.go
@@ -5,8 +5,10 @@ import (
 	"context"
 	"database/sql"
 	"encoding/json"
+	"errors"
 	"fmt"
 	"log/slog"
+	"time"
 
 	"go.uber.org/fx"
 
@@ -129,6 +131,12 @@ func (svc *Service) HandleWebhook(
 	return nil
 }
 
+// cancelRetryDelay is the time to wait after cancelling a deploy before retrying.
+const cancelRetryDelay = 2 * time.Second
+
+// cancelRetryAttempts is the maximum number of times to retry after cancelling.
+const cancelRetryAttempts = 30
+
 func (svc *Service) triggerDeployment(
 	ctx context.Context,
 	app *models.App,
@@ -144,6 +152,25 @@ func (svc *Service) triggerDeployment(
 		deployCtx := context.WithoutCancel(ctx)
 
 		deployErr := svc.deploy.Deploy(deployCtx, app, &eventID)
+		if deployErr != nil && errors.Is(deployErr, deploy.ErrDeploymentInProgress) {
+			// Cancel the in-progress deployment and retry
+			svc.log.Info("cancelling in-progress deployment for new webhook trigger", "app", appName)
+			svc.deploy.CancelAppDeploy(app.ID)
+
+			// Retry until the lock is released by the cancelled deploy
+			for attempt := range cancelRetryAttempts {
+				time.Sleep(cancelRetryDelay)
+
+				svc.log.Info("retrying deployment after cancel",
+					"app", appName, "attempt", attempt+1)
+
+				deployErr = svc.deploy.Deploy(deployCtx, app, &eventID)
+				if deployErr == nil || !errors.Is(deployErr, deploy.ErrDeploymentInProgress) {
+					break
+				}
+			}
+		}
+
 		if deployErr != nil {
 			svc.log.Error("deployment failed", "error", deployErr, "app", appName)
 		}