Matusz went 1-4 with a 2.94 ERA in 58 appearances out of the bullpen last season. He struck out 59 over 49 innings.
The 28-year-old Matusz has a career record of 27-41 with a 4.76 ERA in seven seasons.
Matusz asked for $4.4 million and the Orioles offered $3.5 million before the compromise.
Closer Zach Britton is the only remaining Orioles arbitration eligible player.