Gilbert played his high school hockey for Minnesota powerhouse Bloomington Jefferson High School and was the captain his senior year, 2001. That same year, he switched to forward from defense, which he played as a sophomore and junior.[2]
Due to injuries, Gilbert was called-up to the NHL in January 2007 and made his NHL debut on his 24th birthday against the San Jose Sharks.[citation needed] He scored his first NHL goal on February 20, 2007, against the Ottawa Senators' Martin Gerber in the final seconds of the game to send it to overtime.[4]
On March 4, 2008, Gilbert surpassed Paul Coffey and Marc-André Bergeron for the Oilers' franchise record for most goals scored by a rookie defenseman in a season with his tenth, which came on the power play against Dan Ellis of the Nashville Predators.[5] On April 11, 2008, Gilbert signed a six-year, $24 million contract extension with the Oilers.[6]
After the lockout-shortened 2012–13 season, with the Wild experiencing cap constraints, Gilbert was used as compliance buyout of the remaining two-year of his contract, to be released as a free agent on July 3, 2013.[8]
In September 2013, Gilbert attended the Florida Panthers' pre-season training camp as a free agent, later signing a one-year deal with the club on September 28.[9] He established a regular position within the blueline for the Panthers in 2013–14, and by season's end had produced his best season since 2009, with 28 points in 73 games.
On July 1, 2014, having rediscovered his form with the Panthers, Gilbert signed a two-year contract as an unrestricted free agent with the Montreal Canadiens.[10]
Upon expiry of his contract in Montreal, Gilbert signed a 1 year, $1.4 million contract to join his fifth NHL club, the Los Angeles Kings on July 1, 2016.[11] On February 15, 2017, he was traded two weeks before the trade deadline to the Washington Capitals in exchange for a conditional 5th round draft pick (condition not met, pick not transferred).[12] He played out the season with the Capitals AHL affiliate, the Hershey Bears.
As a free agent, Gilbert left North America after 10 seasons in agreeing to a one-year deal with German outfit, the Thomas Sabo Ice Tigers of the DEL, on July 21, 2017.[13] He signed an extension with the team on July 3, 2018.[14]