As a youth, Barker played in the 2000
Quebec International Pee-Wee Hockey Tournament with the Winnipeg South Monarchs
minor ice hockey team. He later played AAA Midget Hockey for the Winnipeg Thrashers at age 14. After that season he was drafted 4th overall in the 2001 WHL Bantam Draft by the Medicine Hat Tigers. The following season, Barker moved east to play for the Gloucester Rangers and eventually the Cornwall (ON) Colts Jr.A. club of the Central Junior Hockey League (CJHL) before signing with the Tigers at the end of the same 2001–02 season. Barker began his
junior hockey career in
2001–02 with the
Medicine Hat Tigers of the
Western Hockey League (WHL), appearing in three games. In the
following season, he led his team in scoring among defencemen with 47 points and was named to the WHL All-Rookie Team. He improved to a junior career-high 65 points in 60 games in
2003–04, leading the Tigers to a
President's Cup championship. As WHL champions, they earned a berth in the
2004 Memorial Cup, however, Medicine Hat was defeated by the
Gatineau Olympiques in the semi-final. He was drafted third overall by the
Chicago Blackhawks in the
2004 NHL entry draft and was signed to an entry-level contract by Chicago on August 22, 2005. He made the Blackhawks opening roster out of training camp in
2005–06 and made his
NHL debut against the
Colorado Avalanche, but was returned after one game to Medicine Hat, where he completed the season with 18 points in 26 games. After recovering, he joined the
Norfolk Admirals, Chicago's
American Hockey League (AHL) affiliate, making his Norfolk debut on November 3, 2006. He recorded his first professional point on November 21 against the
Manchester Monarchs, assisting on the
game-winning overtime goal. A few games later, he scored his first professional goal on November 29 against the
Bridgeport Sound Tigers in a 6–3 loss. Later in the season, he was called up by the Blackhawks and scored his first NHL goal on January 14, 2007, against the
Minnesota Wild. He finished his rookie season playing in 35 games with Chicago and recording 8 points. Despite finishing his rookie season with the Blackhawks, he was reassigned to the AHL to begin
2007–08. Joining the
Rockford IceHogs in their inaugural AHL season (the team previously played in the
United Hockey League), he assisted on the first-ever goal in IceHogs AHL history on October 6, 2007, against the
Quad City Flames. Barker had been selected to play at the 2008
AHL All-Star Classic, but did not attend as he was once again recalled by the Blackhawks. In his second stint with the Blackhawks, he improved to six goals and 18 points in 45 games. After 7 games with Rockford, he was called up by the Blackhawks and remained with the team. Barker finished the season with six goals, 34 assists, and a
plus-minus of -6. With Barker becoming a
restricted free agent in the off-season, the
NHL Players Association filed a grievance on July 6, 2009, against the Blackhawks on Barker's behalf for not extending a qualifying offer by the required deadline. As such, the NHLPA argued that Barker (as well as five other Blackhawks players in the same situation) qualified as an
unrestricted free agent and could entertain offers from other teams around the league. The Blackhawks quickly came to terms with Barker the same day, re-signing him to a three-year contract worth
US$9.25 million. Given salary cap constraints caused by having to overpay Barker and others, he was traded on February 12, 2010, to the
Minnesota Wild for defenceman
Kim Johnsson and defensive prospect
Nick Leddy. He was placed on waivers by Minnesota on June 28, 2011, to buy out his contract. Barker signed a one-year contract worth $2.25 million with the
Edmonton Oilers on July 1, 2011. On June 25, 2012, he was not tendered a contract and released as a free agent by the Oilers. In September 2012, Barker was invited to the AHL's
Texas Stars training camp and later made it to the main roster. Barker marked his first return to the AHL since 2008 by debuting for the Stars to start the
2012–13 season, on October 13 in a game against
San Antonio Rampage. After 23 games with Texas, his professional try-out was not extended and he left the team. On January 13, 2013, Barker signed a one-year contract worth $700,000 with the
Vancouver Canucks. Barker was not re-signed by the Canucks and became an unrestricted free agent on July 5, 2013. On November 5, 2013, Barker signed a one-year deal with
Barys Astana of the
Kontinental Hockey League (KHL). After spending the 2013–14 season in the KHL, Barker returned to North America and attended training camp with the Blackhawks on a player tryout offer. However, on September 27, 2014, the Blackhawks announced that they had released Barker, leaving him as an unrestricted free agent. On December 22, 2014, Barker signed a contract until the end of the
2014–15 KHL season with
HC Slovan Bratislava, and then had his contract renewed for the
2015–16 season. He left Bratislava after two years to return to
Barys Astana in May 2016. After another shortened stint with Slovan Bratislava, Barker left the KHL and signed with the
SCL Tigers of the Swiss
National League (NL) on January 12, 2018, until the end of the
2017-18 season. In November 2018, he signed a contract until the end of season (including a try-out until the end of November) with
Ilves Tampere but after playing seven games, his contract was terminated on try-out. After spending his last two professional seasons in
France with the
Dragons de Rouen of the
Ligue Magnus, Barker ended his 15-year playing career by retiring and accepting an assistant coaching role with a junior Canadian club, the
Penticton Vees of the
British Columbia Hockey League (BCHL), on June 23, 2021. == International play ==