diff --git a/forms/admin_upsert.go b/forms/admin_upsert.go
index b1212c09..1180b480 100644
--- a/forms/admin_upsert.go
+++ b/forms/admin_upsert.go
@@ -57,6 +57,7 @@ func (form *AdminUpsert) Validate() error {
 				form.admin.IsNew(),
 				validation.Length(models.DefaultIdLength, models.DefaultIdLength),
 				validation.Match(idRegex),
+				validation.By(validators.UniqueId(form.dao, form.admin.TableName())),
 			).Else(validation.In(form.admin.Id)),
 		),
 		validation.Field(
diff --git a/forms/collection_upsert.go b/forms/collection_upsert.go
index ca18948e..48ea4927 100644
--- a/forms/collection_upsert.go
+++ b/forms/collection_upsert.go
@@ -9,6 +9,7 @@ import (
 	validation "github.com/go-ozzo/ozzo-validation/v4"
 	"github.com/pocketbase/pocketbase/core"
 	"github.com/pocketbase/pocketbase/daos"
+	"github.com/pocketbase/pocketbase/forms/validators"
 	"github.com/pocketbase/pocketbase/models"
 	"github.com/pocketbase/pocketbase/models/schema"
 	"github.com/pocketbase/pocketbase/resolvers"
@@ -93,6 +94,7 @@ func (form *CollectionUpsert) Validate() error {
 				form.collection.IsNew(),
 				validation.Length(models.DefaultIdLength, models.DefaultIdLength),
 				validation.Match(idRegex),
+				validation.By(validators.UniqueId(form.dao, form.collection.TableName())),
 			).Else(validation.In(form.collection.Id)),
 		),
 		validation.Field(
diff --git a/forms/record_upsert.go b/forms/record_upsert.go
index ce32e6f8..4a8e8020 100644
--- a/forms/record_upsert.go
+++ b/forms/record_upsert.go
@@ -455,6 +455,7 @@ func (form *RecordUpsert) Validate() error {
 				form.record.IsNew(),
 				validation.Length(models.DefaultIdLength, models.DefaultIdLength),
 				validation.Match(idRegex),
+				validation.By(validators.UniqueId(form.dao, form.record.TableName())),
 			).Else(validation.In(form.record.Id)),
 		),
 	}
diff --git a/forms/validators/model.go b/forms/validators/model.go
new file mode 100644
index 00000000..928207d5
--- /dev/null
+++ b/forms/validators/model.go
@@ -0,0 +1,38 @@
+package validators
+
+import (
+	"database/sql"
+	"errors"
+
+	validation "github.com/go-ozzo/ozzo-validation/v4"
+	"github.com/pocketbase/dbx"
+	"github.com/pocketbase/pocketbase/daos"
+)
+
+// Compare checks whether the provided model id exists.
+//
+// Example:
+//	validation.Field(&form.Id, validation.By(validators.UniqueId(form.dao, tableName)))
+func UniqueId(dao *daos.Dao, tableName string) validation.RuleFunc {
+	return func(value any) error {
+		v, _ := value.(string)
+		if v == "" {
+			return nil // nothing to check
+		}
+
+		var foundId string
+
+		err := dao.DB().
+			Select("id").
+			From(tableName).
+			Where(dbx.HashExp{"id": v}).
+			Limit(1).
+			Row(&foundId)
+
+		if !errors.Is(err, sql.ErrNoRows) || foundId != "" {
+			return validation.NewError("validation_invalid_id", "The model id is invalid or already exists.")
+		}
+
+		return nil
+	}
+}
diff --git a/forms/validators/model_test.go b/forms/validators/model_test.go
new file mode 100644
index 00000000..45b486d5
--- /dev/null
+++ b/forms/validators/model_test.go
@@ -0,0 +1,34 @@
+package validators_test
+
+import (
+	"testing"
+
+	"github.com/pocketbase/pocketbase/forms/validators"
+	"github.com/pocketbase/pocketbase/tests"
+)
+
+func TestUniqueId(t *testing.T) {
+	app, _ := tests.NewTestApp()
+	defer app.Cleanup()
+
+	scenarios := []struct {
+		id          string
+		tableName   string
+		expectError bool
+	}{
+		{"", "", false},
+		{"test", "", true},
+		{"wsmn24bux7wo113", "_collections", true},
+		{"test_unique_id", "unknown_table", true},
+		{"test_unique_id", "_collections", false},
+	}
+
+	for i, s := range scenarios {
+		err := validators.UniqueId(app.Dao(), s.tableName)(s.id)
+
+		hasErr := err != nil
+		if hasErr != s.expectError {
+			t.Errorf("(%d) Expected hasErr to be %v, got %v (%v)", i, s.expectError, hasErr, err)
+		}
+	}
+}