Beaulieu completed his fifth season with the Canadiens in 2016-17.
A former first-round pick from 2011, the 24-year-old rearguard registered four goals and 24 assists in 74 games during his most recent campaign. He also took part in five playoff games, picking up an assist with a minus-3 differential duyring the postseason.
With Buffalo's pick, the Habs now hold six picks heading into this month's draft.
