Thayer signed a minor league contract with the Orioles on Wednesday that includes an invitation to spring training.
Thayer spent the past four seasons in the Padres bullpen, but was designated for assignment in August after posting a disappointing 4.06 ERA and 3.6 BB/9 in 37.2 innings. He'll compete for a spot in the bullpen, although he'll have to pitch better than he did in 2015 if he wants to make the 25-man roster.