diff --git a/CHANGES.md b/CHANGES.md
index c8d3eb97e889..e87cd3baf213 100644
--- a/CHANGES.md
+++ b/CHANGES.md
@@ -80,7 +80,7 @@
 
 ## Bugfixes
 
-* Fixed X (Java/Python) ([#X](https://github.com/apache/beam/issues/X)).
+* Avoids Cassandra syntax error when user-defined query has no where clause in it (Java) ([#24829](https://github.com/apache/beam/issues/24829)).
 
 ## Known Issues
 
diff --git a/sdks/java/io/cassandra/src/main/java/org/apache/beam/sdk/io/cassandra/ReadFn.java b/sdks/java/io/cassandra/src/main/java/org/apache/beam/sdk/io/cassandra/ReadFn.java
index 6bca1cf3d177..3bb536029187 100644
--- a/sdks/java/io/cassandra/src/main/java/org/apache/beam/sdk/io/cassandra/ReadFn.java
+++ b/sdks/java/io/cassandra/src/main/java/org/apache/beam/sdk/io/cassandra/ReadFn.java
@@ -141,6 +141,9 @@ private static String buildInitialQuery(Read<?> spec, Boolean hasRingRange) {
     return (spec.query() == null)
         ? String.format("SELECT * FROM %s.%s", spec.keyspace().get(), spec.table().get())
             + " WHERE "
-        : spec.query().get() + (hasRingRange ? " AND " : "");
+        : spec.query().get()
+            + (hasRingRange
+                ? spec.query().get().toUpperCase().contains("WHERE") ? " AND " : " WHERE "
+                : "");
   }
 }
diff --git a/sdks/java/io/cassandra/src/test/java/org/apache/beam/sdk/io/cassandra/CassandraIOTest.java b/sdks/java/io/cassandra/src/test/java/org/apache/beam/sdk/io/cassandra/CassandraIOTest.java
index 7196556abc7c..a472b9ee1c3a 100644
--- a/sdks/java/io/cassandra/src/test/java/org/apache/beam/sdk/io/cassandra/CassandraIOTest.java
+++ b/sdks/java/io/cassandra/src/test/java/org/apache/beam/sdk/io/cassandra/CassandraIOTest.java
@@ -458,6 +458,11 @@ public KV<String, Integer> apply(Scientist scientist) {
 
   @Test
   public void testReadWithQuery() throws Exception {
+    String query =
+        String.format(
+            "select person_id, writetime(person_name) from %s.%s where person_id=10 AND person_department='logic'",
+            CASSANDRA_KEYSPACE, CASSANDRA_TABLE);
+
     PCollection<Scientist> output =
         pipeline.apply(
             CassandraIO.<Scientist>read()
@@ -466,8 +471,7 @@ public void testReadWithQuery() throws Exception {
                 .withKeyspace(CASSANDRA_KEYSPACE)
                 .withTable(CASSANDRA_TABLE)
                 .withMinNumberOfSplits(20)
-                .withQuery(
-                    "select person_id, writetime(person_name) from beam_ks.scientist where person_id=10 AND person_department='logic'")
+                .withQuery(query)
                 .withCoder(SerializableCoder.of(Scientist.class))
                 .withEntity(Scientist.class));
 
@@ -485,6 +489,39 @@ public void testReadWithQuery() throws Exception {
     pipeline.run();
   }
 
+  @Test
+  public void testReadWithUnfilteredQuery() throws Exception {
+    String query =
+        String.format(
+            "select person_id, writetime(person_name) from %s.%s",
+            CASSANDRA_KEYSPACE, CASSANDRA_TABLE);
+
+    PCollection<Scientist> output =
+        pipeline.apply(
+            CassandraIO.<Scientist>read()
+                .withHosts(Collections.singletonList(CASSANDRA_HOST))
+                .withPort(cassandraPort)
+                .withKeyspace(CASSANDRA_KEYSPACE)
+                .withTable(CASSANDRA_TABLE)
+                .withMinNumberOfSplits(20)
+                .withQuery(query)
+                .withCoder(SerializableCoder.of(Scientist.class))
+                .withEntity(Scientist.class));
+
+    PAssert.thatSingleton(output.apply("Count", Count.globally())).isEqualTo(NUM_ROWS);
+    PAssert.that(output)
+        .satisfies(
+            input -> {
+              for (Scientist sci : input) {
+                assertNull(sci.name);
+                assertTrue(sci.nameTs != null && sci.nameTs > 0);
+              }
+              return null;
+            });
+
+    pipeline.run();
+  }
+
   @Test
   public void testWrite() {
     ArrayList<ScientistWrite> data = new ArrayList<>();