diff --git a/airflow/config_templates/config.yml b/airflow/config_templates/config.yml
index 007ceadd6788b..621589d2a5877 100644
--- a/airflow/config_templates/config.yml
+++ b/airflow/config_templates/config.yml
@@ -2042,21 +2042,6 @@ webserver:
       type: integer
       example: "10"
       default: "5"
-    allow_raw_html_descriptions:
-      description: |
-        A DAG author is able to provide any raw HTML into ``doc_md`` or params description in
-        ``description_md`` for text formatting. This is including potentially unsafe javascript.
-        Displaying the DAG or trigger form in web UI provides the DAG author the potential to
-        inject malicious code into clients browsers. To ensure the web UI is safe by default,
-        raw HTML is disabled by default. If you trust your DAG authors, you can enable HTML
-        support in markdown by setting this option to ``True``.
-
-        This parameter also enables the deprecated fields ``description_html`` and
-        ``custom_html_form`` in DAG params until the feature is removed in a future version.
-      version_added: 2.8.0
-      type: boolean
-      example: "False"
-      default: "False"
     allowed_payload_size:
       description: |
         The maximum size of the request payload (in MB) that can be sent.
diff --git a/airflow/www/templates/airflow/trigger.html b/airflow/www/templates/airflow/trigger.html
index eb098dd21d076..86e0b4eb4565a 100644
--- a/airflow/www/templates/airflow/trigger.html
+++ b/airflow/www/templates/airflow/trigger.html
@@ -42,9 +42,7 @@
     : </label>
   </td>
   <td>
-    {% if "custom_html_form" in form_details.schema %}
-      {{ form_details.schema.custom_html_form | replace("{name}", "element_" + form_key) | replace("{value}", form_details.value) }}
-    {% elif "type" in form_details.schema and form_details.schema.type == "boolean" %}
+    {% if "type" in form_details.schema and form_details.schema.type == "boolean" %}
       <label for="element_{{ form_key }}" control-label="">
         <input class="switch-input" name="element_{{ form_key }}" id="element_{{ form_key }}" type="checkbox"
           {%- if form_details.value %} checked="checked"{%- endif -%}/>
diff --git a/airflow/www/utils.py b/airflow/www/utils.py
index 413d9fe2b6b83..37c559055886f 100644
--- a/airflow/www/utils.py
+++ b/airflow/www/utils.py
@@ -39,7 +39,6 @@
 from sqlalchemy import delete, func, select, types
 from sqlalchemy.ext.associationproxy import AssociationProxy
 
-from airflow.configuration import conf
 from airflow.exceptions import RemovedInAirflow3Warning
 from airflow.models.dagrun import DagRun
 from airflow.models.dagwarning import DagWarning
@@ -639,7 +638,7 @@ def json_render(obj, lexer):
 
 def wrapped_markdown(s, css_class="rich_doc"):
     """Convert a Markdown string to HTML."""
-    md = MarkdownIt("gfm-like", {"html": conf.getboolean("webserver", "allow_raw_html_descriptions")})
+    md = MarkdownIt("gfm-like", {"html": False})
     if s is None:
         return None
     s = textwrap.dedent(s)
diff --git a/airflow/www/views.py b/airflow/www/views.py
index d7b670303c86f..c34554d5082b0 100644
--- a/airflow/www/views.py
+++ b/airflow/www/views.py
@@ -2059,8 +2059,6 @@ def trigger(self, dag_id: str, session: Session = NEW_SESSION):
 
         # Prepare form fields with param struct details to render a proper form with schema information
         form_fields = {}
-        allow_raw_html_descriptions = conf.getboolean("webserver", "allow_raw_html_descriptions")
-        form_trust_problems = []
         for k, v in dag.params.items():
             form_fields[k] = v.dump()
             form_field: dict = form_fields[k]
@@ -2078,19 +2076,6 @@ def trigger(self, dag_id: str, session: Session = NEW_SESSION):
                     form_field_schema["type"] = ["array", "null"]
                 elif isinstance(form_field_value, dict):
                     form_field_schema["type"] = ["object", "null"]
-            # Mark HTML fields as safe if allowed
-            if allow_raw_html_descriptions:
-                if "description_html" in form_field_schema:
-                    form_field["description"] = Markup(form_field_schema["description_html"])
-                if "custom_html_form" in form_field_schema:
-                    form_field_schema["custom_html_form"] = Markup(form_field_schema["custom_html_form"])
-            else:
-                if "description_html" in form_field_schema and "description_md" not in form_field_schema:
-                    form_trust_problems.append(f"Field {k} uses HTML description")
-                    form_field["description"] = form_field_schema.pop("description_html")
-                if "custom_html_form" in form_field_schema:
-                    form_trust_problems.append(f"Field {k} uses custom HTML form definition")
-                    form_field_schema.pop("custom_html_form")
             if "description_md" in form_field_schema:
                 form_field["description"] = wwwutils.wrapped_markdown(form_field_schema["description_md"])
             # Check for default values and pre-populate
@@ -2110,34 +2095,6 @@ def trigger(self, dag_id: str, session: Session = NEW_SESSION):
                         )
                 else:
                     form_field["value"] = request.values.get(k)
-        if form_trust_problems:
-            flash(
-                Markup(
-                    "At least one field in the trigger form uses a raw HTML form definition. This is not allowed for "
-                    "security. Please switch to markdown description via <code>description_md</code>. "
-                    "Raw HTML is deprecated and must be enabled via "
-                    "<code>webserver.allow_raw_html_descriptions</code> configuration parameter. Using plain text "
-                    "as fallback for these fields. "
-                    f"<ul><li>{'</li><li>'.join(form_trust_problems)}</li></ul>"
-                ),
-                "warning",
-            )
-        if allow_raw_html_descriptions and any("description_html" in p.schema for p in dag.params.values()):
-            flash(
-                Markup(
-                    "The form params use raw HTML in <code>description_html</code> which is deprecated. "
-                    "Please migrate to <code>description_md</code>."
-                ),
-                "warning",
-            )
-        if allow_raw_html_descriptions and any("custom_html_form" in p.schema for p in dag.params.values()):
-            flash(
-                Markup(
-                    "The form params use <code>custom_html_form</code> definition. "
-                    "This is deprecated with Airflow 2.8.0 and will be removed in a future release."
-                ),
-                "warning",
-            )
 
         ui_fields_defined = any("const" not in f["schema"] for f in form_fields.values())
         show_trigger_form_if_no_params = conf.getboolean("webserver", "show_trigger_form_if_no_params")
diff --git a/docs/apache-airflow/core-concepts/params.rst b/docs/apache-airflow/core-concepts/params.rst
index a4efceb3664c9..9de7e0df0e0c3 100644
--- a/docs/apache-airflow/core-concepts/params.rst
+++ b/docs/apache-airflow/core-concepts/params.rst
@@ -388,14 +388,10 @@ For examples, please take a look at the two example DAGs provided: :ref:`Params
     The trigger form can also be forced to be displayed also if no params are defined using the configuration switch
     ``webserver.show_trigger_form_if_no_params``.
 
-.. versionchanged:: 2.8.0
-    By default custom HTML is not allowed to prevent injection of scripts or other malicious HTML code. If you trust your DAG authors
-    you can change the trust level of parameter descriptions to allow raw HTML by setting the configuration entry
-    ``webserver.allow_raw_html_descriptions`` to ``True``. With the default setting all HTML will be displayed as plain text.
-    This relates to the previous feature to enable rich formatting with the attribute ``description_html`` which is now super-seeded
-    with the attribute ``description_md``.
-    Custom form elements using the attribute ``custom_html_form`` allow a DAG author to specify raw HTML form templates. These
-    custom HTML form elements are deprecated as of version 2.8.0.
+.. versionchanged:: 3.0.0
+    By default custom HTML is not allowed to prevent injection of scripts or other malicious HTML code. The previous field named
+    ``description_html`` is now super-seeded with the attribute ``description_md``. ``description_html`` is not supported anymore.
+    Custom form elements using the attribute ``custom_html_form`` was deprecated in version 2.8.0 and support was removed in 3.0.0.
 
 Disabling Runtime Param Modification
 ------------------------------------
diff --git a/newsfragments/40029.significant.rst b/newsfragments/40029.significant.rst
new file mode 100644
index 0000000000000..e64f5170efda1
--- /dev/null
+++ b/newsfragments/40029.significant.rst
@@ -0,0 +1 @@
+Removed deprecated ``allow_raw_html_descriptions`` option from UI Trigger forms.
diff --git a/tests/www/test_utils.py b/tests/www/test_utils.py
index 669f08a2b6158..f7470c8c68832 100644
--- a/tests/www/test_utils.py
+++ b/tests/www/test_utils.py
@@ -45,7 +45,6 @@
     wrapped_markdown,
 )
 from airflow.www.widgets import AirflowDateTimePickerROWidget, BS3TextAreaROWidget, BS3TextFieldROWidget
-from tests.test_utils.config import conf_vars
 
 
 class TestUtils:
@@ -504,53 +503,19 @@ def test_wrapped_markdown_with_nested_list(self):
             == rendered
         )
 
-    def test_wrapped_markdown_with_collapsible_section(self):
-        with conf_vars({("webserver", "allow_raw_html_descriptions"): "true"}):
-            rendered = wrapped_markdown(
-                """
-# A collapsible section with markdown
-<details>
-  <summary>Click to expand!</summary>
-
-  ## Heading
-  1. A numbered
-  2. list
-     * With some
-     * Sub bullets
-</details>
-            """
-            )
-
-            assert (
-                """<div class="rich_doc" ><h1>A collapsible section with markdown</h1>
-<details>
-  <summary>Click to expand!</summary>
-<h2>Heading</h2>
-<ol>
-<li>A numbered</li>
-<li>list
-<ul>
-<li>With some</li>
-<li>Sub bullets</li>
-</ul>
-</li>
-</ol>
-</details>
-</div>"""
-                == rendered
-            )
-
-    @pytest.mark.parametrize("allow_html", [False, True])
-    def test_wrapped_markdown_with_raw_html(self, allow_html):
-        with conf_vars({("webserver", "allow_raw_html_descriptions"): str(allow_html)}):
-            HTML = "test <code>raw HTML</code>"
-            rendered = wrapped_markdown(HTML)
-            if allow_html:
-                assert HTML in rendered
-            else:
-                from markupsafe import escape
+    @pytest.mark.parametrize(
+        "html",
+        [
+            "test <code>raw HTML</code>",
+            "hidden <script>alert(1)</script> nuggets.",
+        ],
+    )
+    def test_wrapped_markdown_with_raw_html(self, html):
+        """Ensure that HTML code is not ending-up in markdown but is always escaped."""
+        from markupsafe import escape
 
-                assert escape(HTML) in rendered
+        rendered = wrapped_markdown(html)
+        assert escape(html) in rendered
 
     @pytest.mark.parametrize(
         "dag_run,expected_val",
diff --git a/tests/www/views/test_views_trigger_dag.py b/tests/www/views/test_views_trigger_dag.py
index 9b2b2971982af..01b6713600af3 100644
--- a/tests/www/views/test_views_trigger_dag.py
+++ b/tests/www/views/test_views_trigger_dag.py
@@ -34,7 +34,7 @@
 from airflow.utils.types import DagRunType
 from tests.test_utils.api_connexion_utils import create_test_client
 from tests.test_utils.config import conf_vars
-from tests.test_utils.www import check_content_in_response, check_content_not_in_response
+from tests.test_utils.www import check_content_in_response
 
 pytestmark = pytest.mark.db_test
 
@@ -273,55 +273,6 @@ def test_trigger_dag_params_render(admin_client, dag_maker, session, app, monkey
     )
 
 
-@pytest.mark.parametrize("allow_html", [False, True])
-def test_trigger_dag_html_allow(admin_client, dag_maker, session, app, monkeypatch, allow_html):
-    """
-    Test that HTML is escaped per default in description.
-    """
-    from markupsafe import escape
-
-    DAG_ID = "params_dag"
-    HTML_DESCRIPTION1 = "HTML <code>raw code</code>."
-    HTML_DESCRIPTION2 = "HTML <code>in md text</code>."
-    expect_escape = not allow_html
-    with conf_vars({("webserver", "allow_raw_html_descriptions"): str(allow_html)}):
-        param1 = Param(
-            42,
-            description_html=HTML_DESCRIPTION1,
-            type="integer",
-            minimum=1,
-            maximum=100,
-        )
-        param2 = Param(
-            42,
-            description_md=HTML_DESCRIPTION2,
-            type="integer",
-            minimum=1,
-            maximum=100,
-        )
-        with monkeypatch.context() as m:
-            with dag_maker(
-                dag_id=DAG_ID, serialized=True, session=session, params={"param1": param1, "param2": param2}
-            ):
-                EmptyOperator(task_id="task1")
-
-            m.setattr(app, "dag_bag", dag_maker.dagbag)
-            resp = admin_client.get(f"dags/{DAG_ID}/trigger")
-
-        if expect_escape:
-            check_content_in_response(escape(HTML_DESCRIPTION1), resp)
-            check_content_in_response(escape(HTML_DESCRIPTION2), resp)
-            check_content_in_response(
-                "At least one field in the trigger form uses a raw HTML form definition.", resp
-            )
-        else:
-            check_content_in_response(HTML_DESCRIPTION1, resp)
-            check_content_in_response(HTML_DESCRIPTION2, resp)
-            check_content_not_in_response(
-                "At least one field in the trigger form uses a raw HTML form definition.", resp
-            )
-
-
 def test_trigger_endpoint_uses_existing_dagbag(admin_client):
     """
     Test that Trigger Endpoint uses the DagBag already created in views.py