Following her shakedown, Mayrant operated briefly off the New England coast before departing Newport for a southerly cruise in late October. She arrived at Guantánamo Bay on 9 January 1912, participated in winter exercises in the Caribbean and then, as a unit of the Torpedo Florida, Atlantic Fleet, remained in the area, calling at various gulf and Caribbean ports until spring. Returning to Newport on 14 May, she continued to operate off the East Coast and in the Caribbean until 1915. Then, after completion of the 1915 winter exercises off Cuba, she steamed to the Navy Yard, Brooklyn, for overhaul prior to decommissioning 20 May.
On 9 November 1915 Mayrant was moved to Philadelphia where she was berthed until recommissioning on 2 January 1918. Joining the wartime fleet in the spring, the destroyer was employed as an escort ship, operating along the coast and across the Atlantic. Following the Armistice, she cruised south for winter maneuvers and then cruised off the middle Atlantic coast until entering the Navy Yard at Charleston for a second preinactivation overhaul on 21 June 1919. Departing Charleston 16 July she sailed back to Philadelphia where she decommissioned for a final time 12 December 1919.
Designated DD 31 on 17 July 1920, Mayrant remained berthed at Philadelphia as a unit of the Reserve Fleet until 1935. On 8 March of that year she was struck from the Naval Register; on 28 June she was sold to M. Block & Co., Norfolk, Virginia; and on 21 August her hulk was scrapped.