diff --git a/rdflib/plugins/serializers/longturtle.py b/rdflib/plugins/serializers/longturtle.py
index 2aaed36e6d..1e68e68495 100644
--- a/rdflib/plugins/serializers/longturtle.py
+++ b/rdflib/plugins/serializers/longturtle.py
@@ -22,7 +22,7 @@
 
 from rdflib.compare import to_canonical_graph
 from rdflib.exceptions import Error
-from rdflib.graph import Graph
+from rdflib.graph import Graph, _TripleType
 from rdflib.namespace import RDF
 from rdflib.term import BNode, Literal, URIRef
 
@@ -149,11 +149,20 @@ def serialize(
 
         self.base = None
 
-    def preprocessTriple(self, triple):
+    def preprocessTriple(self, triple: _TripleType) -> None:
         super(LongTurtleSerializer, self).preprocessTriple(triple)
         for i, node in enumerate(triple):
-            if node in self.keywords:
-                continue
+            if i == VERB:
+                if node in self.keywords:
+                    # predicate is a keyword
+                    continue
+                if (
+                    self.base is not None
+                    and isinstance(node, URIRef)
+                    and node.startswith(self.base)
+                ):
+                    # predicate corresponds to base namespace
+                    continue
             # Don't use generated prefixes for subjects and objects
             self.getQName(node, gen_prefix=(i == VERB))
             if isinstance(node, Literal) and node.datatype:
@@ -180,6 +189,8 @@ def getQName(self, uri, gen_prefix=True):
 
         prefix, namespace, local = parts
 
+        local = local.replace(r"(", r"\(").replace(r")", r"\)")
+
         # QName cannot end with .
         if local.endswith("."):
             return None
diff --git a/rdflib/plugins/serializers/turtle.py b/rdflib/plugins/serializers/turtle.py
index d1dfcf4a67..abee2e43b4 100644
--- a/rdflib/plugins/serializers/turtle.py
+++ b/rdflib/plugins/serializers/turtle.py
@@ -263,9 +263,17 @@ def serialize(
     def preprocessTriple(self, triple: _TripleType) -> None:
         super(TurtleSerializer, self).preprocessTriple(triple)
         for i, node in enumerate(triple):
-            if i == VERB and node in self.keywords:
-                # predicate is a keyword
-                continue
+            if i == VERB:
+                if node in self.keywords:
+                    # predicate is a keyword
+                    continue
+                if (
+                    self.base is not None
+                    and isinstance(node, URIRef)
+                    and node.startswith(self.base)
+                ):
+                    # predicate corresponds to base namespace
+                    continue
             # Don't use generated prefixes for subjects and objects
             self.getQName(node, gen_prefix=(i == VERB))
             if isinstance(node, Literal) and node.datatype:
diff --git a/test/test_serializers/test_serializer_turtle_base_namespace.py b/test/test_serializers/test_serializer_turtle_base_namespace.py
new file mode 100644
index 0000000000..f0971611d8
--- /dev/null
+++ b/test/test_serializers/test_serializer_turtle_base_namespace.py
@@ -0,0 +1,34 @@
+from rdflib import Graph, Namespace, URIRef
+
+# https://github.com/RDFLib/rdflib/issues/3237
+# Test that the ns1 prefix is not generated when the base is set.
+mns = Namespace("http://my-namespace.net/")
+
+
+def test_turtle():
+    g = Graph(base="http://my-base.net/")
+    g.add((mns.foo, URIRef("http://my-base.net/my-predicate"), mns.bar))
+    result = g.serialize(format="text/turtle")
+    assert (
+        result
+        == """@base <http://my-base.net/> .
+
+<http://my-namespace.net/foo> <my-predicate> <http://my-namespace.net/bar> .
+
+"""
+    )
+
+
+def test_longturtle():
+    g = Graph(base="http://my-base.net/")
+    g.add((mns.foo, URIRef("http://my-base.net/my-predicate"), mns.bar))
+    result = g.serialize(format="longturtle", canon=True)
+    assert (
+        result
+        == """BASE <http://my-base.net/>
+
+<http://my-namespace.net/foo>
+    <my-predicate> <http://my-namespace.net/bar> ;
+.
+"""
+    ), print(result)