She operated on various trans-oceanic lines, including a circulary Halifax-New York-Copenhagen-Gdańsk-Liepāja. In 1930 she was bought by Polish Transatlantic Ship Association and renamed SS Kościuszko. She arrived at Gdynia on June 8, 1930 and on June 20 the Polish banner was raised. Initially with a mixed Polish-Danish crew, after 1931 the ship's was crew was entirely Polish. SS Kościuszko served on the Gdynia-Copenhagen-Halifax line, as well as a tourist ship for shorter cruises. The company in 1934 was renamed to Gdynia America Line and used the ship (as well as her sister ship ) on trans-Atlantic lines. In 1935 SS Kościuszko started to operate the Constanţa-Haifa line and in October 1936 on a line to South America. Rendered obsolete by the more modern MS Batory and MS Piłsudski, in early 1939 she was withdrawn from service.
During World War II she was mobilized by the Polish Navy and was evacuated to Dartmouth prior to the outbreak of the Polish Defensive War. On November 10, 1939 she was commissioned under the new name of ORP Gdynia. Initially serving as a troop transport, she was considered unsuitable for service at sea and served instead as a base ship in the United Kingdom. She housed a canteen, a hospital, a Naval NCO school and several other offices. During that period she was visited by, among others, Winston Churchill and King George VI. During the German air raid on Denver, Norfolk, of September 25, she was hit by two aerial bombs, but swift action by the crew prevented the ship from catching fire. On June 30, 1941 she was decommissioned and returned to Polish merchant marine under her old name. Chartered to the British Lamport and Holt Line, she served as a troop transport in the Indian Ocean and Malaya. She was attacked by Japanese aircraft several times and in 1943 was hit by a torpedo, which however did not explode.
Withdrawn to the Mediterranean, she took part in the Allied Invasion of Sicily. Then she returned to Indian Ocean, this time as a part of United Maritime Authority. In April 1946 she was sold to the Liverpool-based Lamport and Holt Line, renamed to SS Empire Helford and continued to serve as a troop transport and for transportation of displaced persons. In 1949 she was withdrawn from service and was scrapped the following year in Blyth.