Martinez, 27, has played an important role in each of the Kings' Stanley Cup wins, and has appeared in 221 career games with the franchise. He has tallied 25 goals and 62 points since making his Kings debut during the 2009-10 season.
Martinez, who was set to become an unrestricted free agent on July 1, has two goals and seven points through 18 games this season.
Selected in the fourth round of the 2007 NHL draft, Martinez's most notable moment with the Kings came when he scored the series-clinching goal against the New York Rangers in Game 5 of the Stanley Cup Final in June. He also scored the winning goal in Game 7 of the 2014 Western Conference finals against the Chicago Blackhawks.
Martinez isn't the only player who will be under contract with the Kings for a while. Drew Doughty is signed through 2018-19 and Jake Muzzin, who signed a five-year extension last month, is under contract through 2019-20.
Dustin Brown, Jonathan Quick, Jeff Carter and Marian Gaborik each are under deals that stretch beyond 2020.
Times staff writer Lisa Dillman contributed to this report.