The trade was made Tuesday, less than a week before opening day.
The 26-year-old Asher was 2-7 with a 5.88 ERA in 12 big league starts for the Phillies in 2015 and 2016. He served an 80-game suspension for steroid use last season, when he went 2-1 with a 2.88 ERA in five starts.
"Good, young arm with options," manager Buck Showalter said. "I think the plan is for him to come to camp with us and see if we can work him in for an outing. He's had some challenges he's gotten behind."
The Orioles optioned right-handed starter Mike Wright to Triple-A Norfolk. Wright had an 8.38 ERA this spring.