| Date/Season | Transaction |
|---|
| 1/21/2021 | San Jose Sharks send Dan Sexton, CBJ 2026 Rnd 2 to the Ottawa Senators for Brendan Gallagher, $500,000 |
| 9/19/2020 | New York Rangers send Brendan Gallagher, PHI 2025 Rnd 3 to the Ottawa Senators for Dillon Dube |
| 9/13/2020 | New York Rangers send Sergei Andronov to the Buffalo Sabres for Brendan Gallagher |
| 9/8/2020 | Washington Capitals send Brendan Gallagher, John Gaudreau, BOS 2026 Rnd 2 to the Buffalo Sabres for Erik Gudbranson, $1,000,000 |
| 8/16/2017 | Washington Capitals send Richard Bachman, MON 2022 Rnd 2, WSH 2027 Rnd 3 to the Philadelphia Flyers for Brendan Gallagher, ANA 2022 Rnd 2, PHI 2027 Rnd 2, $750,000 |
| 2/2/2016 | Philadelphia Flyers send Brandon Dubinsky, Seth Jones to the Buffalo Sabres for Aleksander Barkov, Brendan Gallagher |
| 2018 | Drafted in the 1st round, 6th overall by Buffalo |
