| TRADE : From Kings to Bruins : Y:2021-RND:2-LAK. |
| TRADE : From Bruins to Kings : Y:2021-RND:4-LAK. |
| TRADE : From Blues to Bruins : Andy Greene (73). |
| TRADE : From Bruins to Blues : Jarred Tinordi (66)- Y:2021-RND:3-TOR- Y:2021-RND:6-BOS. |
| TRADE : From Bruins to Wild : Pat Maroon (66). |
| TRADE : From Oilers to Bruins : Nico Hischier (71)- Y:2021-RND:4-CAL- Y:2021-RND:8-SEA. |
| TRADE : From Bruins to Oilers : Ryan O\'Rouke (P)- Tim Stutzle (P)- Y:2021-RND:2-NSH. |
| TRADE : From Bruins to Oilers : Garret Sparks (59). |
| TRADE : From Oilers to Bruins : Danil Savunov (P)- Y:2021-RND:5-EDM. |
| TRADE : From Bruins to Predators : Magnus Chrona (P)- Y:2022-RND:7-BOS. |
| TRADE : From Predators to Bruins : Y:2021-RND:4-LAK. |
| TRADE : From Bruins to Predators : Sven Baertschi (66)- Y:2023-RND:3-BOS. |
| TRADE : From Predators to Bruins : Jakob Stukel (55)- Y:2021-RND:3-WIN. |
| TRADE : From Avalanche to Bruins : Jordan Binnington (75)- Y:2021-RND:2-COL. |
| TRADE : From Bruins to Avalanche : Alexei Toropchenko (54)- Travis Barron (50)- Dmitry Voronkov (P)- Y:2021-RND:1-BOS. |
| Pascal Aquin was added to Bruins. |
| TRADE : From Islanders to Bruins : Paul Stastny (71). |
| TRADE : From Bruins to Islanders : Blake Lizotte (63)- Charles Hudon (59)- Y:2021-RND:3-BOS. |
| Bruins drafts Donovan Sebrango as the #99 overall pick in the Entry Draft of year 2020. |
| Bruins drafts Calle Clang as the #104 overall pick in the Entry Draft of year 2020. |
