In
| Derek Forbort, D | Free Agent – Winnipeg |
| Erik Haula, LW/C | Free Agent – Nashville |
| Tomas Nosek, LW/C | Free Agent – Vegas |
| Linus Ullmark, G | Free Agent – Buffalo |
| Troy Grosenick, G | Free Agent – Los Angeles |
| Nick Foligno, W/C | Free Agent – Toronto |
| Tyler Lewington, D | Free Agent – Nashville |
| Steven Fogarty, W/C | Free Agent – Buffalo |
| James Greenway, D | Trade – Toronto |
Out
| Nick Ritchie, LW | Free Agent – Toronto |
| Ondrej Kase, LW/RW | Free Agent – Toronto |
| Jaroslav Halak, G | Free Agent – Vancouver |
| Sean Kuraly, C/LW | Free Agent – Columbus |
| Jarred Tinordi, D | Free Agent – NY Rangers |
| Greg McKegg, C | Free Agent – NY Rangers |
| Dan Vladar, G | Trade – Calgary |
| Robert Lantosi, RW | Free Agent – Europe |
| Jeremy Lauzon, D | Expansion Draft – Seattle |
| Kevan Miller, D | Retired |
| Steven Kampfer, D | Free Agent – Europe |
| Paul Carey, LW/C | Free Agent – Europe |
Unrestricted Free Agents – Patrice Bergeron, Curtis Lazar, Jesper Froden, Steven Fogarty, Troy Grosenick, Tyler Lewington and Linus Arnesson
Restricted Free Agents – Jake DeBrusk, Charlie McAvoy, Jakub Zboril, Jack Ahcan, Urho Vaakanainen, Matt Filipe, Oskar Steen, Jack Studnicka, Anton Blidh, Callum Booth, Cameron Hughes, Joona Koppanen, Nick Wolff, Kyle Keyser, Karson Kuhlman
1st round – Boston
2nd round – Boston
3rd round – Calgary
4th round – Boston
5th round – Boston
6th round – Boston
7th round – Boston
Boston Bruins Roster
2021-2022 Boston Bruins Schedule
