diff --git a/cloudinit/config/schemas/schema-network-config-v1.json b/cloudinit/config/schemas/schema-network-config-v1.json
index 43097af4858..efcbf8a0d47 100644
--- a/cloudinit/config/schemas/schema-network-config-v1.json
+++ b/cloudinit/config/schemas/schema-network-config-v1.json
@@ -503,6 +503,10 @@
           "type": "string",
           "description": "IPv4 subnet mask in dotted format or CIDR notation"
         },
+        "broadcast": {
+          "type": "string",
+          "description": "IPv4 broadcast address in dotted format."
+        },
         "gateway": {
           "type": "string",
           "description": "IPv4 address of the default gateway for this subnet."
diff --git a/doc/rtd/reference/network-config-format-v1.rst b/doc/rtd/reference/network-config-format-v1.rst
index 42f2dc2265a..db5ccbe158a 100644
--- a/doc/rtd/reference/network-config-format-v1.rst
+++ b/doc/rtd/reference/network-config-format-v1.rst
@@ -296,6 +296,8 @@ Valid keys for ``subnets`` include the following:
   interface will be handled during boot.
 - ``address``: IPv4 or IPv6 address. It may include CIDR netmask notation.
 - ``netmask``: IPv4 subnet mask in dotted format or CIDR notation.
+- ``broadcast`` : IPv4 broadcast address in dotted format. This is
+  only rendered if :file:`/etc/network/interfaces` is used.
 - ``gateway``: IPv4 address of the default gateway for this subnet.
 - ``dns_nameservers``: Specify a list of IPv4 dns server IPs to end up in
   :file:`resolv.conf`.