The Kings signed Westgarth to a two-year, $1.45 million deal on Monday, keeping the physical forward under contract through the 2013-14 season.
Westgarth won his first NHL job as the Kings' enforcer last season, recording three points and 105 penalty minutes in 56 games. He also played in two postseason games against San Jose, and the experience left him hungry to evolve into an NHL regular.
He has yet to score a goal in 65 NHL games over the last two seasons.
"I'm ecstatic to extend my time here," Westgarth said after a training camp workout. "It's a really special group of people who are going to do some great things in the next couple of years."
The 27-year-old Princeton product signed with the Kings as a free agent in 2007, working his way through the minor league system before cracking the Los Angeles roster a year ago. He has developed a friendly rivalry with Anaheim enforcer George Parros, who's also a former Princeton player.
Early in the summer, Westgarth married Meagan Cowher, a former Princeton basketball player and the daughter of former Pittsburgh Steelers coach Bill Cowher.
Westgarth said he spent the rest of the summer preparing for camp, reaching new goals in conditioning and strength while working on his "all-around game."
Westgarth has been singled out by teammates during camp for his offseason conditioning and improved speed.
"I feel better than I ever have before, by a long shot," Westgarth said. "It's a lot easier (going into camp) just being around the same group of guys again. You get to know the guys a lot better and just get a little more confident."
Information from ESPNLosAngeles.com's Dan Arritt and The Associated Press was used in this report.