diff --git a/django/db/models/fields/__init__.py b/django/db/models/fields/__init__.py
index ab4c094c1c..7ea2fd59aa 100644
--- a/django/db/models/fields/__init__.py
+++ b/django/db/models/fields/__init__.py
@@ -2248,7 +2248,7 @@ class NullBooleanField(BooleanField):
             "NullBooleanField is removed except for support in historical "
             "migrations."
         ),
-        "hint": "Use BooleanField(null=True) instead.",
+        "hint": "Use BooleanField(null=True, blank=True) instead.",
         "id": "fields.E903",
     }
 
diff --git a/docs/releases/3.1.txt b/docs/releases/3.1.txt
index 50430ec1be..789a65efaa 100644
--- a/docs/releases/3.1.txt
+++ b/docs/releases/3.1.txt
@@ -821,7 +821,7 @@ Miscellaneous
   :class:`~django.db.models.expressions.RawSQL` instead beforehand.
 
 * The ``NullBooleanField`` model field is deprecated in favor of
-  ``BooleanField(null=True)``.
+  ``BooleanField(null=True, blank=True)``.
 
 * ``django.conf.urls.url()`` alias of :func:`django.urls.re_path` is
   deprecated.
diff --git a/tests/invalid_models_tests/test_deprecated_fields.py b/tests/invalid_models_tests/test_deprecated_fields.py
index 7b1e3fb7ac..429e15febc 100644
--- a/tests/invalid_models_tests/test_deprecated_fields.py
+++ b/tests/invalid_models_tests/test_deprecated_fields.py
@@ -59,7 +59,7 @@ class DeprecatedFieldsTests(SimpleTestCase):
                 checks.Error(
                     "NullBooleanField is removed except for support in historical "
                     "migrations.",
-                    hint="Use BooleanField(null=True) instead.",
+                    hint="Use BooleanField(null=True, blank=True) instead.",
                     obj=NullBooleanFieldModel._meta.get_field("nb"),
                     id="fields.E903",
                 ),