On February 4, 2005, Coburn tied a WHL record for most goals by a defenceman in a game with four against the Seattle Thunderbirds in a 7–4 win.

During Coburn's time in the WHL, he also competed in two World Junior Championships for Canada, winning silver in 2004 and gold in 2005.

However, Fleury's clearing attempt went off Coburn and into his own net, giving the Americans a 4–3 advantage that eventually won them both the game and the gold medal.

[2] After several years in the Thrashers organization, during which Coburn split his time between the NHL and the Thrashers' minor league affiliate, the Chicago Wolves of the American Hockey League (AHL), Coburn was traded on February 24, 2007 (the NHL trade deadline) to the Philadelphia Flyers in exchange for defenceman Alexei Zhitnik.

In the midst of the Flyers' 2008 Stanley Cup playoff run, Coburn was injured on May 11, 2008, two minutes into Game 2 of the Eastern Conference Final against the Pittsburgh Penguins when a deflected puck hit him above the eye.

With a year remaining on his contract, approaching the delayed 2020–21 season and with the Lightning under salary cap constraints, Coburn was traded after six seasons in Tampa Bay along with Cédric Paquette and a 2022 second-round pick to the Ottawa Senators in exchange for Anders Nilsson and the contract of Marián Gáborík on December 27, 2020.