The agreement Wednesday allows the 27-year-old left-hander to earn $300,000 in performance bonuses based on games finished: $50,000 each for 40, 45 and 55, and $75,000 apiece for 50 and 60.
Eligible for arbitration for the first time, Britton had asked for $4.2 million and had been offered $3.2 million when the sides exchanged figures last month. The settlement was at the midpoint.
Britton became the Orioles' closer last year and was 3-2 with a 1.65 ERA and 37 saves in 41 chances for the AL East champions, finishing 49 games. He made $521,500.
Outfielder Alejandro de Aza is Baltimore's only remaining player in arbitration.