diff --git a/changes/4193.feature b/changes/4193.feature
new file mode 100644
index 00000000000..325ec5b7db3
--- /dev/null
+++ b/changes/4193.feature
@@ -0,0 +1 @@
+Allow sysadmins to change usernames of other accounts
diff --git a/ckan/logic/action/update.py b/ckan/logic/action/update.py
index 418f42398f7..c68e02de6db 100644
--- a/ckan/logic/action/update.py
+++ b/ckan/logic/action/update.py
@@ -774,7 +774,7 @@ def user_update(context: Context, data_dict: DataDict) -> ActionResult.UserUpdat
     '''Update a user account.
 
     Normal users can only update their own user accounts. Sysadmins can update
-    any user account. Can not modify exisiting user's name.
+    any user account and modify existing usernames.
 
     .. note:: Update methods may delete parameters not explicitly provided in the
         data_dict. If you want to edit only a specific attribute use `user_patch`
diff --git a/ckan/logic/validators.py b/ckan/logic/validators.py
index b8c9f409e99..55209751091 100644
--- a/ckan/logic/validators.py
+++ b/ckan/logic/validators.py
@@ -14,7 +14,7 @@
 from sqlalchemy.orm.exc import NoResultFound
 
 import ckan.lib.navl.dictization_functions as df
-import ckan.logic as logic
+from ckan import authz, logic
 import ckan.logic.converters as converters
 import ckan.lib.helpers as h
 from ckan.model import (MAX_TAG_LENGTH, MIN_TAG_LENGTH,
@@ -22,7 +22,6 @@
                         PACKAGE_VERSION_MAX_LENGTH,
                         VOCABULARY_NAME_MAX_LENGTH,
                         VOCABULARY_NAME_MIN_LENGTH)
-import ckan.authz as authz
 from ckan.model.core import State
 
 from ckan.common import _
@@ -615,10 +614,13 @@ def user_name_validator(key: FlattenKey, data: FlattenDataDict,
             return
         else:
             # Otherwise return an error: there's already another user with that
-            # name, so you can create a new user with that name or update an
+            # name, so you can't create a new user with that name or update an
             # existing user's name to that name.
             errors[key].append(_('That login name is not available.'))
     elif user_obj_from_context:
+        requester = context.get('auth_user_obj', None)
+        if requester and authz.is_sysadmin(requester.name):
+            return
         old_user = model.User.get(user_obj_from_context.id)
         if old_user is not None and old_user.state != model.State.PENDING:
             errors[key].append(_('That login name can not be modified.'))
diff --git a/ckan/templates/user/edit_user_form.html b/ckan/templates/user/edit_user_form.html
index 3b1a3331888..01e68715288 100644
--- a/ckan/templates/user/edit_user_form.html
+++ b/ckan/templates/user/edit_user_form.html
@@ -8,7 +8,11 @@
     {% block core_fields %}
       <fieldset>
         <legend>{{ _('Change details') }}</legend>
-        {{ form.input('name', label=_('Username'), id='field-username', value=data.name, error=errors.name, classes=['control-medium'], attrs={'readonly': '', 'class': 'form-control'}) }}
+        {% if g.userobj.sysadmin %}
+          {{ form.input('name', label=_('Username'), id='field-username', value=data.name, error=errors.name, classes=['control-medium'], is_required=true) }}
+        {% else %}
+          {{ form.input('name', label=_('Username'), id='field-username', value=data.name, error=errors.name, classes=['control-medium'], attrs={'readonly': '', 'class': 'form-control'}) }}
+        {% endif %}
 
         {{ form.input('fullname', label=_('Full name'), id='field-fullname', value=data.fullname, error=errors.fullname, placeholder=_('eg. Joe Bloggs'), classes=['control-medium']) }}
 
diff --git a/ckan/tests/controllers/test_user.py b/ckan/tests/controllers/test_user.py
index 13ca9509af4..dcc3f20af98 100644
--- a/ckan/tests/controllers/test_user.py
+++ b/ckan/tests/controllers/test_user.py
@@ -428,6 +428,24 @@ def test_edit_user_logged_in_username_change_by_id(self, app, user):
 
         assert "That login name can not be modified" in response
 
+    def test_edit_user_logged_in_username_change_by_sysadmin(
+            self, app, user, sysadmin):
+
+        headers = {"Authorization": sysadmin["token"]}
+        response = app.post(
+            url=url_for("user.edit", id=user["id"]),
+            data={
+                "email": user["email"],
+                "save": "",
+                "old_password": "correct123",
+                "password1": "",
+                "password2": "",
+                "name": factories.User.stub().name,
+            },
+            headers=headers
+        )
+        assert 'Profile updated' in response
+
     def test_perform_reset_for_key_change(self, app):
         password = "TestPassword1"
         params = {"password1": password, "password2": password}