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. The trade is often considered one of the more lopsided trades in recent NHL history, as Coburn went on to become one of the Flyers' top defenders while Zhitnik failed to meet expectations and was bought out one year later. The following season, in 2007–08, Coburn emerged with an 8-goal, 36-point season with Philadelphia. 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. The resulting gash required 50 stitches to be closed, and Coburn did not return for the rest of the series. On July 1, 2010, Coburn signed a two-year contract extension with the Flyers. Philadelphia later extended Coburn on November 9, 2011, at a rate of $18 million over four years, a $4.5 million annual cap hit. Approaching the 2014–15 trade deadline, with the Flyers on the outside of a 2015 playoff position, Coburn was traded to the Tampa Bay Lightning in exchange for defenceman Radko Gudas and a first- and third-round selection in 2015 NHL Entry Draft on March 2, 2015. On February 26, 2016, Tampa Bay signed Coburn to a three-year, $11.1 million contract extension. On October 15, 2016, Coburn skated in his 700th career NHL game, a 3–2 Lightning win over the visiting New Jersey Devils. On June 18, 2019, Tampa Bay extended Coburn’s contract for an additional 2 years at $3.4 million. Despite a reduced role, appearing in 40 regular season games for 4 points and 3 playoff games, he was a member of the 2019–20 team who won the Stanley Cup. 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. Coburn was traded from the Senators to the New York Islanders on April 11, 2021, for a seventh-round pick in the 2022 NHL Entry Draft. On November 12, 2021,