diff --git a/pkg/certmanager/cache_store.go b/pkg/certmanager/cache_store.go
index a515d6d81..a47fa2632 100644
--- a/pkg/certmanager/cache_store.go
+++ b/pkg/certmanager/cache_store.go
@@ -59,8 +59,13 @@ func (w *CacheStore) WarmCache(ctx context.Context) error {
 	err := w.pg.WithConn(
 		ctx,
 		func(ctx context.Context, conn pg.Querier) error {
+			var caches coredata.CachedCertificates
+			if err := caches.DeleteUnreferenced(ctx, conn); err != nil {
+				return fmt.Errorf("cannot delete unreferenced certificate cache: %w", err)
+			}
+
 			certificates := coredata.Certificates{}
-			if err := certificates.LoadActive(ctx, conn, coredata.NewNoScope()); err != nil {
+			if err := certificates.LoadActiveReferenced(ctx, conn, coredata.NewNoScope()); err != nil {
 				return fmt.Errorf("cannot load active certificates: %w", err)
 			}
 
diff --git a/pkg/certmanager/selector.go b/pkg/certmanager/selector.go
index 0deaf15df..379d84805 100644
--- a/pkg/certmanager/selector.go
+++ b/pkg/certmanager/selector.go
@@ -23,6 +23,7 @@ package certmanager
 import (
 	"context"
 	"crypto/tls"
+	"errors"
 	"fmt"
 	"sync"
 	"time"
@@ -89,6 +90,10 @@ func (s *Selector) loadFromDatabase(domain string) (*tls.Certificate, error) {
 	err := s.pg.WithConn(
 		ctx,
 		func(ctx context.Context, conn pg.Querier) error {
+			if err := requireRoutableDomain(ctx, conn, domain); err != nil {
+				return err
+			}
+
 			var cache coredata.CachedCertificate
 			if err := cache.LoadByDomain(ctx, conn, domain); err != nil {
 				if err := s.rebuildCacheEntry(ctx, conn, domain); err != nil {
@@ -123,6 +128,10 @@ func (s *Selector) loadFromDatabase(domain string) (*tls.Certificate, error) {
 }
 
 func (s *Selector) rebuildCacheEntry(ctx context.Context, conn pg.Querier, domain string) error {
+	if err := requireRoutableDomain(ctx, conn, domain); err != nil {
+		return err
+	}
+
 	var certificate coredata.Certificate
 	if err := certificate.LoadByHostname(ctx, conn, coredata.NewNoScope(), domain); err != nil {
 		return fmt.Errorf("cannot load certificate: %w", err)
@@ -167,3 +176,22 @@ func (s *Selector) rebuildCacheEntry(ctx context.Context, conn pg.Querier, domai
 
 	return nil
 }
+
+// requireRoutableDomain ensures the SNI hostname still maps to a custom domain
+// row. Orphaned certificates left after domain deletion must not be served.
+func requireRoutableDomain(ctx context.Context, conn pg.Querier, domain string) error {
+	var customDomain coredata.CustomDomain
+	if err := customDomain.LoadByDomain(ctx, conn, coredata.NewNoScope(), domain); err != nil {
+		if errors.Is(err, coredata.ErrResourceNotFound) {
+			return err
+		}
+
+		return fmt.Errorf("cannot load custom domain: %w", err)
+	}
+
+	if customDomain.CertificateID == nil {
+		return coredata.ErrResourceNotFound
+	}
+
+	return nil
+}
diff --git a/pkg/coredata/cached_certificate.go b/pkg/coredata/cached_certificate.go
index 258074937..609d6a062 100644
--- a/pkg/coredata/cached_certificate.go
+++ b/pkg/coredata/cached_certificate.go
@@ -170,6 +170,29 @@ WHERE
 	return nil
 }
 
+// DeleteUnreferenced removes cache entries whose certificate is no longer
+// referenced by any custom domain, so deleted domains cannot keep a usable
+// TLS cache entry.
+func (cc *CachedCertificates) DeleteUnreferenced(ctx context.Context, conn pg.Querier) error {
+	q := `
+DELETE FROM
+	cached_certificates
+WHERE
+	NOT EXISTS (
+		SELECT 1
+		FROM custom_domains
+		WHERE custom_domains.certificate_id = cached_certificates.certificate_id
+	)
+`
+
+	_, err := conn.Exec(ctx, q, pgx.NamedArgs{})
+	if err != nil {
+		return fmt.Errorf("cannot delete unreferenced certificate cache: %w", err)
+	}
+
+	return nil
+}
+
 func (cc *CachedCertificate) RefreshFromCertificate(ctx context.Context, conn pg.Querier, certificate *Certificate, encryptionKey cipher.EncryptionKey) error {
 	if certificate.SSLCertificate == nil {
 		return fmt.Errorf("certificate has no parsed certificate")
diff --git a/pkg/coredata/certificate.go b/pkg/coredata/certificate.go
index 17f9861eb..fadb130a4 100644
--- a/pkg/coredata/certificate.go
+++ b/pkg/coredata/certificate.go
@@ -685,7 +685,10 @@ WHERE
 	return nil
 }
 
-func (certificates *Certificates) LoadActive(
+// LoadActiveReferenced loads active certificates that are still referenced by
+// at least one custom domain. Certificates left behind after a domain is
+// deleted must not be warmed into the TLS cache or served by SNI alone.
+func (certificates *Certificates) LoadActiveReferenced(
 	ctx context.Context,
 	conn pg.Querier,
 	scope Scoper,
@@ -714,6 +717,11 @@ WHERE
 	%s
 	AND status = @status
 	AND ssl_certificate IS NOT NULL
+	AND EXISTS (
+		SELECT 1
+		FROM custom_domains
+		WHERE custom_domains.certificate_id = certificates.id
+	)
 `
 
 	q = fmt.Sprintf(q, scope.SQLFragment())
@@ -723,7 +731,7 @@ WHERE
 
 	rows, err := conn.Query(ctx, q, args)
 	if err != nil {
-		return fmt.Errorf("cannot query active certificates: %w", err)
+		return fmt.Errorf("cannot query active referenced certificates: %w", err)
 	}
 
 	result, err := pgx.CollectRows(rows, pgx.RowToAddrOfStructByName[Certificate])