diff --git a/docs/topics/request-response.rst b/docs/topics/request-response.rst
index a0d9fc03e..7af180bdf 100644
--- a/docs/topics/request-response.rst
+++ b/docs/topics/request-response.rst
@@ -1203,6 +1203,8 @@ TextResponse objects
 
     .. autoattribute:: TextResponse.attributes
 
+    .. autoattribute:: TextResponse.base_url
+
     :class:`TextResponse` objects support the following methods in addition to
     the standard :class:`Response` ones:
 
diff --git a/scrapy/http/response/text.py b/scrapy/http/response/text.py
index 8b12578d3..6e3f8a926 100644
--- a/scrapy/http/response/text.py
+++ b/scrapy/http/response/text.py
@@ -95,7 +95,13 @@ class TextResponse(Response):
 
     @property
     def base_url(self) -> str:
-        """Base URL"""
+        """Base URL for any relative URL in the response.
+
+        It defaults to the response :attr:`~scrapy.http.Response.url`, but HTML
+        responses may include a `base element
+        <https://developer.mozilla.org/en-US/docs/Web/HTML/Element/base>`_ with
+        a different base URL.
+        """
         if self._cached_base_url is None:
             self._cached_base_url = get_base_url(
                 self.text[:4096],