The Yankees made the deal Sunday during their 4-2 win over the Chicago White Sox. The Phillies designated the right-hander for assignment Wednesday.
Qualls was 1-1 with a 4.60 ERA in a team-high 35 appearances for the Phillies. Righty batters are hitting .250 (19 for 76) against him this year.
"He's kind of a guy that can get up to 95 mph, somewhat of a power guy, a sinker guy," Yankees manager Joe Girardi said. "Very tough on right-handers."
The Yankees could be looking to add a veteran arm to a relief corps that has been hit hard by injuries. Closer Mariano Rivera is out for the season with a torn ligament in his knee and eighth-inning setup man David Robertson recently returned from a stint on the disabled list and faltered in the second of back-to-back outings.
Cory Wade has also struggled in his last several appearances.
"We mix and match a little bit here so we hope he's really effective for us," Girardi said.
To make room for Qualls on the 40-man roster, the Yankees designated minor league infielder Matt Antonelli for assignment.