After a strong season in 1999-00 with the Plymouth Whalers of the OHL, Justin Williams was drafted in the first round of the 2000 NHL Entry Draft by the Philadelphia Flyers. That fall, he was a full-time member of the NHL squad.
Born in Cobourg, Ontario on October 4, 1981, Williams scored his first NHL goal in his very first NHL game. That season as a rookie, Williams finished with 25 points in spite of suffering a broken hand partway through the season. In 2001-02, Williams increased his point total, collecting 40, and won the Pelle Lindbergh Memorial Trophy as the most improved Flyer.
Injuries limited the talented young forward to a mere 41 games during the 2002-03 season. After tallying 26 points in his first 47 games in 2003-04, Williams was dealt to the Carolina Hurricanes, after the Flyers had lost two defensemen to injury and needed to fill in the holes on the blue line, thus acquiring Danny Markov from Carolina.
A season after the lockout saw Williams compete in his most productive season, recording a career high 76 points in 82 games. The young forward continued to produce in the post season in 2005-06 as his 18 points tied him for third best on a Carolina Hurricane team that won the Stanley Cup in 2005-06.
On the international stage, Williams represented Canada at the 2002 World Championships and helped his nation capture gold at the 2004 and 2007 Championships.
On March 4, 2009, NHL's trade deadline, Williams was shipped from Carolina to Los Angeles as part of a three team trade that also included the Edmonton Oilers.
In 2011-12, Williams was a key part of the Los Angeles Kings club that stormed through the Western Conference playoffs and defeated the New Jersey Devils to capture the first Stanley Cup in franchise history. Along with veteran leadership, Williams chipped in with 15 points in 20 playoff games.
In 2014, Williams became a three-time Stanley Cup winner and would add the Conn Smythe Trophy to his collection. With nine goals and 16 assists in 26 playoff games, Williams helped lead the Kings to their second Stanley Cup title in three seasons.
Williams continued to further his reputation as a "big game player" during the 2014 Stanley Cup Playoffs. He notched five points in the Kings three Game Seven wins and established a new NHL record with 14 career points in Game Sevens.
After seven seasons with the Los Angeles Kings, Williams left as an unrestricted free agent to sign a two year contract with the Washington Capitals.