Westgarth mainly played as an enforcer, as evidenced by his NHL career statistics of only 16 points and 266 penalty minutes in 169 games.

[1] He attended General Amherst High School, where he participated in ice hockey, soccer, tennis, and golf.

At 6 feet 4 inches (193 cm) and 235 pounds (107 kilograms), he was the tallest and heaviest player on the Princeton team.

In his second year with Princeton, he was moved up to the third line with junior Sebastian Borza and freshman Landis Stankievech.

Immediately following the signing, he was assigned to their American Hockey League (AHL) affiliate, the Manchester Monarchs.

[25] He made his professional debut on March 18, 2007 with the Monarchs, just two days after signing with the Kings, against the Providence Bruins.

Westgarth made his NHL debut for the Kings on January 20, 2009 logging 4:39 of ice-time on the road against the Minnesota Wild.

[28] Westgarth's strong campaign earned him a roster spot with the Kings in the fall of 2010, as the enforcer for head coach Terry Murray.

Westgarth's first fight of the preseason resulted in facial fractures for Colorado Avalanche winger David Koci on September 22.

[29] Through 30 games, Westgarth led the Kings in penalty minutes with 59, after a number of fights with fellow NHL enforcers, such as John Scott of the Chicago Blackhawks.

[30] During the 2011–12 season, Westgarth scored his first NHL goal against Kari Lehtonen in a 3-2 overtime loss to the Dallas Stars on November 23, 2011.

With the Flames opting to not tender Westgarth a new offer, he was released to free agency at season's end.

Without a contract heading into the 2014–15 season, Westgarth accepted an invitation to try out at the Edmonton Oilers training camp.