The Penguins acquired Roberts from Florida for defenseman Noah Welch. They got Laraque from Phoenix for forward prospect Daniel Carcillo and a low-round draft pick.
Laraque told Canada's TSN sports channel that the trade was a done deal, although the team had not yet announced it.
Roberts gives Pittsburgh a steadying, proven hand to complement Mark Recchi, the only veteran goal-producer in a lineup led by 19-year-old Sidney Crosby, 20-year-old Evgeni Malkin and 18-year-old Jordan Staal.
The NHL's best-known enforcer, Laraque spent several days weighing whether to waive his no-trade clause _ as did Roberts. By Tuesday, Laraque decided he couldn't pass up the chance to join what may be the NHL's best collection of youthful scorers since Wayne Gretzky's Oilers in the early 1980s.
"Teams know that to beat the Penguins, you have to hit Sidney Crosby, hit Evgeni Malkin, hit Jordan Staal," Laraque told Canada's TSN sports channel. "I'm up for the challenge to (protect them). I'm real excited. ... I know I'm going to be a lot busier and have more responsibility. They have more than one guy to target."
The 30-year-old Laraque is signed for $1.3 million for next season, and he would have to waive his no-trade clause again for Pittsburgh to trade him.
"I'm excited to go help the Penguins," Laraque said of a much-improved team that is contending for the first time in six seasons and recently gained points in 16 consecutive games, going 14-0-2.
With two new forwards arriving, the Penguins freed up ice time for them by dealing forward Dominic Moore to the Minnesota Wild for a third-round draft pick.
Crosby, on the verge of his second 100-point season in the NHL, has been increasingly singled out for physical attention. Islanders forward Jason Blake closed out a game by spearing an unsuspecting Crosby in the stomach and Montreal's Maxim Lapierre drilled him the stomach immediately after an opening faceoff.
Laraque is best known for fighting and drawing penalties _ he has 878 penalty minutes in 546 games _ but can also score an occasional goal. He has five goals and 17 assists in 56 games this season.
Penguins general manager Ray Shero, looking to supplement a much-improved team that went into Tuesday night's game against New Jersey nine points out of the Atlantic Division lead, spent plenty of time Monday trying to persuade Roberts to waive his no-trade clause.
Roberts initially wanted to be dealt only to Toronto or Ottawa. He also didn't want to be a rent-a-player and preferred a contract for next season, but he and the Penguins have had no such talks yet.
"Ray really did a great job to get him here," said Recchi, who recently told the AP that the Penguins were close to being a Stanley Cup challenger but lacked some of the veteran presence of last year's Cup-winning Carolina Hurricanes.
Roberts has 421 goals and 451 assists in 1,127 career games with Calgary, Carolina, Toronto and Florida. Roberts has played in 108 games since last season with 27 goals and 47 assists and is plus-9 during that span. This season, he has 13 goals and 16 assists in 50 games.