Coffey, 31, was 5-1 with a 3.82 ERA for Washington in 2011, pitching 59 2/3 innings in 69 appearances and earned $1.35 million.
After last month's elbow surgery for Blake Hawksworth, Coffey will provide veteran depth to a bullpen that generally is relying on young arms, with Javy Guerra and Kenley Jansen closing, Josh Lindblom the long man and Scott Elbert the primary left-hander. He will join veterans Matt Guerrier and Mike MacDougal in middle relief, with John Grabow a non-roster invitee.
Ronald Belisario is a wild card in the bullpen equation. After missing all of 2011 he remains on the restricted list, but he is already working out in Arizona. Belisario is subject to a 25-game suspension for violating MLB's drug policy.
Ken Gurnick is a reporter for MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.