Iginla's base salary is $1.8 million and the contract carries incentives of $4.2 million for an annual salary-cap figure of $6 million.
Iginla appeared in 44 games in 2012-13 between the Flames and Penguins, scoring 14 goals and adding 19 assists. He went 4-8-12 in 15 games in the Stanley Cup Playoffs, where the Penguins were swept by the Bruins in the Eastern Conference Final.
In 1,232 NHL games with the Calgary Flames and Pittsburgh, Iginla has 530 goals, 576 assists and 840 penalty minutes.
Thursday, the Bruins acquired right win Loui Eriksson from the Dallas Stars in a trade that sent away forwards Tyler Seguin and Rich Peverely. Boston also lost forward Nathan Horton, who signed a seven-year contract with the Columbus Blue Jackets.
The Bruins also signed goaltender Chad Johnson to a one-year, one-way contract; forward Bobby Robins to a two-year, two-way contract; forward Nick Johnson to a one-year, two-way deal; and defenseman Mike Moore to a two-way, one-year contract.