In 2002, Blackthorne portrayed British doctor Matt Slingerland on "Presidio Med" and made notable appearances as Guy Morton in the British television series "Holby City", Liam MacGregor in "Peak Practice", Doctor Jeremy Lawson in NBC's "ER" and biological terrorist Stephen Saunders on "24". He also made appearances on "Medium" in two roles (one uncredited as Henry Stoller, Junior), "Deadwood", and an episode of "Monk" Season 5 Episode 10 "Mr. Monk and the Leper" as quirky dermatologist Aaron Polinski. He appeared as Shane Healy, a British musician and husband of Wendy Healy (played by Brooke Shields), in the NBC series "Lipstick Jungle" for two seasons. He played an IRA terrorist in the US series "Burn Notice" in 2009 in one episode. In 2010, he appeared in two episodes of "Leverage" as an arms dealer and in an episode of "" directed by Rob Zombie. Later that year he had a recurring role in "The Gates" as Christian Harper. Also on 7 December 2010, he appeared in the Christmas episode ("Secret Santa") of the SyFy series "Warehouse 13". He appeared in a two-part cliffhanger during the mid-season break of White Collar Season 2.