Converted to a destroyer tender at the New York Navy Yard, and equipped with surplus and salvaged machine tools and shop equipment selected from dismantled U.S. Navy and United States Army war plants in the demobilization after World War I, Altair underwent her metamorphosis in nine months and then fitted out at her conversion yard into late November 1922.

She then proceeded to the west coast of the United States via Newport, Rhode Island; Hampton Roads, Virginia, and the Panama Canal Zone, reaching San Diego, California, on 17 December 1922.

Altair participated in this troop lift, when she and the destroyer tender USS Melville (AD-2) transported Marine Observation Squadron 1 and a rifle company from San Diego to Corinto, a port on the west coast of Nicaragua, reaching their destination on 16 February 1927.

Altair then resumed her operations providing services to the destroyers of Squadron 12, accompanying them to Narragansett Bay in Rhode Island for tactical exercises before ultimately returning once more to San Diego.

En route to her new duty station, she served as plane guard for U.S. Navy Consolidated PBY Catalina flying boats being ferried to Oahu, arriving at Pearl Harbor on 16 April 1940.

Following repairs at the Norfolk Navy Yard in Portsmouth, Virginia, Altair reported to Commander, Operational Training Command, Atlantic Fleet, on 21 August 1943 and soon resumed active tender operations at Bermuda, this time in support of the destroyer and destroyer escort shakedown group (Task Group 23.1) until shifted to Guantanamo Bay Naval Base, Cuba, where she arrived on 11 March 1945.

Laid up in the National Defense Reserve Fleet's Suisun Bay, California, berthing area, the ship remained there until sold on 9 March 1948 to the Basalt Rock Company, which subsequently took delivery of and scrapped her.