On 14 February 1918, Narragansett departed New London and steamed to Wilmington, Delaware, for overhaul and alterations necessary for troop transport service.

On 10 July, she departed New York, in convoy, arriving at Saint-Nazaire and reporting for duty in the Cross Channel Fleet on the 21st.

From that time until the Armistice, Narragansett served as a unit of that fleet, which was charged with the highly important mission of keeping men and materiel, especially coal, flowing from the British Isles to the Continent.

After the Armistice, the transport reversed her mission and commenced carrying troops from France to England.

On 31 January, however, Narragansett, en route to Southampton, went aground due to the Pilot losing his bearings in a snowstorm, on the Bembridge Ledge, Isle of Wight.