The left-handed Britton finished fourth in the American League Cy Young Award balloting last season when he was a perfect 47 of 47 in save opportunities.
Britton recorded a microscopic 0.54 ERA over 69 relief appearances while allowing four earned runs all season. He won the Mariano Rivera Reliever of the Year Award as the AL's top bullpen performer.
Britton has saved 120 games over the past three seasons since being moved to the bullpen and emerging as perhaps the top reliever in the AL.
He is 27-21 with a 3.24 ERA over six seasons with the Orioles.
Britton made $6.75 million last season.
Baltimore also agreed to terms with infielder Ryan Flaherty (one year, $1.8 million) and left-hander T.J. McFarland (one year, $685,000).
Flaherty batted .217 with three homers last season, while McFarland was 2-2 with a 6.93 ERA.