Policy-based, on-demand provisioning of optical transport bandwidth is disclosed. In one of many possible embodiments, a system is provided for policy-based, on-demand provisioning of optical transport bandwidth. The system includes a layer-specific operation support subsystem (OSS) configured to manage network elements that form a sub-network over an optical transport network. The optical transport network provides bandwidth-on-demand provisioning capabilities. The layer-specific OSS includes one or more predefined bandwidth provisioning policies. The layer-specific OSS is configured to selectively request on-demand provisioning of bandwidth on the sub-network based on the predefined bandwidth provisioning policies.