diff --git a/cli/src/main/java/org/onlab/onos/cli/net/ClustersListCommand.java b/cli/src/main/java/org/onlab/onos/cli/net/ClustersListCommand.java
index 2b2953b..f41f85e 100644
--- a/cli/src/main/java/org/onlab/onos/cli/net/ClustersListCommand.java
+++ b/cli/src/main/java/org/onlab/onos/cli/net/ClustersListCommand.java
@@ -1,5 +1,8 @@
 package org.onlab.onos.cli.net;
 
+import com.fasterxml.jackson.databind.JsonNode;
+import com.fasterxml.jackson.databind.ObjectMapper;
+import com.fasterxml.jackson.databind.node.ArrayNode;
 import com.google.common.collect.Lists;
 import org.apache.karaf.shell.commands.Command;
 import org.onlab.onos.cli.Comparators;
@@ -24,9 +27,26 @@
         List<TopologyCluster> clusters = Lists.newArrayList(service.getClusters(topology));
         Collections.sort(clusters, Comparators.CLUSTER_COMPARATOR);
 
-        for (TopologyCluster cluster : clusters) {
-            print(FMT, cluster.id().index(), cluster.deviceCount(), cluster.linkCount());
+        if (outputJson()) {
+            print("%s", json(clusters));
+        } else {
+            for (TopologyCluster cluster : clusters) {
+                print(FMT, cluster.id().index(), cluster.deviceCount(), cluster.linkCount());
+            }
         }
     }
 
+    // Produces a JSON result.
+    private JsonNode json(Iterable<TopologyCluster> clusters) {
+        ObjectMapper mapper = new ObjectMapper();
+        ArrayNode result = mapper.createArrayNode();
+        for (TopologyCluster cluster : clusters) {
+            result.add(mapper.createObjectNode()
+                               .put("id", cluster.id().index())
+                               .put("deviceCount", cluster.deviceCount())
+                               .put("linkCount", cluster.linkCount()));
+        }
+        return result;
+    }
+
 }