He was called up by the Florida Marlins and made his major league debut on September 3, 2007. He spent all of 2008 playing for the Albuquerque Isotopes, the Marlins' Triple-A team and became a free agent at the end of the season.
Seattle Mariners
In December 2008, he signed a minor league contract with the Seattle Mariners. He was granted Free Agency after the 2009 season but decided to re-sign to minor league contract with the Mariners. On July 15, 2010, Seddon was called up by the Mariners.[1] He made his debut for the Mariners 2 days later.
Following the 2010 season, he accepted an invitation to Mariners' spring training.[2]
Cleveland Indians
On January 9, 2012, Seddon signed a minor league contract with the Cleveland Indians. He also received an invitation to spring training.
Seddon's contract was purchased by the Indians on August 5, 2012.[3] He was designated for assignment on November 30, 2012, to make room for Mike McDade.[4]
SK Wyverns
On December 6, 2012, Seddon had his contract sold to the SK Wyverns in South Korea.
Seddon signed with the SK Wyverns for the 2015 season.
Fubon Guardians
Seddon signed with the Fubon Guardians of the Chinese Professional Baseball League for the 2017 season. On June 23, 2017, Seddon was released by the Guardians after struggling to a 5.92 ERA in 65.1 innings pitched.[5]