The pick will become a fourth-rounder if the Bruins advance to the second round of the Stanley Cup Playoffs.
Coyle has 28 points in 60 games this season while averaging over 17 minutes per contest. The 26-year-old will slot in behind Patrice Bergeron and David Krejci down the middle and will provide the Bruins with some offensive depth for the stretch run.
The seven-year veteran is under contract through 2020 at a $3.2-million cap hit.
Donato struggled to carve out a role with Boston this season. The 22-year-old made a name for himself after scoring five goals in five games last year for the United States at the PyeongChang Olympics, but bounced between the Bruins and AHL Providence during the 2018-19 campaign. Donato recorded nine points in 34 games in the NHL this season while chipping in 12 points in 18 contests in the minors.