Brian McGrattan was born September 2, 1981 in Hamilton, Ontario. The fourth round, 104th overall selection of the Los Angeles Kings in the 1999 NHL Entry Draft, McGrattan is a graduate of the OHL.
A hulking forward, McGrattan played five seasons in the OHL with stops in Guelph, Sudbury, Mississauga, Owen Sound, Oshawa and Sault Ste. Marie. After failing to reach a contract agreement with Los Angeles, McGrattan was acquired by the Ottawa Senators in the fall of 2002. Upon his arrival with the Sens organization, McGrattan went on to suit up for the club's AHL affiliate in Binghamton where he would brake the AHL's single-season penalty minute record in 2004-05 with 551 PIM.
In the fall of 2005, McGrattan went on to make his NHL debut with Ottawa. He went on to compete in 60 games with the Sens that year and was a regular in the line-up. Over the next two seasons however, McGrattan's role as an enforcer on the team would diminish. He was a healthy scratch on many nights throughout his 2007-08 campaign.
In the summer of 2008 McGrattan's stint in Ottawa came to an end when the club dealt him to the Phoenix Coyotes in exchange for a 5th round draft pick in 2009.
In the summer of 2009, as an unrestricted free agent, the tough guy inked a deal with the Calgary Flames.
On October 9, 2010, McGratton signed a one-year deal with the Boston Bruins and was assigned to the club's AHL affiliate in Providence.
On February 27, 2011, he was traded to the Anaheim Ducks along with Sean Zimmerman in exchange for David Laliberte and Stefan Chaput.
On July 7, 2011, McGrattan signed a one-year contract with the Anaheim Ducks. On October 11, he was waived by the club and subsequently claimed by the Nashville Predators.
While in the Nashville organization, McGrattan spent the majority of his time in the American Hockey League with the Milwaukee Admirals. On February 28, 2013, McGrattan was traded to the Calgary Flames in exchange for Joe Piskula.