Around 1900, the Lighthouse Board determined that the increased boat traffic to New London harbor warranted a new lighthouse to supplement New London Harbor Light, upriver on Pequot Avenue.
Building of the lighthouse was authorized by the United States Senate in 1906 and in 1908 the contract to build the structure was awarded to the T.A. Scott Company of New London. Total cost allocated for the project was not to exceed $115,000.
Completed in 1909, the lighthouse was originally named Southwest Ledge; however, to avoid confusion with a lighthouse having the same name in New Haven harbor, the name was changed to New London Ledge Light.