The 25-year-old Alberts has appeared in 146 games over the past two seasons for the Bruins, racking up 17 points. He also led the Bruins last year with 124 penalty minutes.
"He is a big, tough and physical player who we think is only going to get better as he continues to develop as a NHL defenceman," GM Peter Chiarelli said in a statement.
Alberts has spent the last four years in the Bruins organization after finishing his college career at Boston College.
He's happy to be staying in the city.
"I am glad that we got this done early during the off-season and now I can concentrate on working out and preparing for next season," said Alberts. "Between my years at Boston College and my time with the Bruins, I have come to love playing in Boston."