Following his retirement as an active player, Blessin joined RB Leipzig as a youth coach in 2012. He left Leipzig in 2020 to accept an offer as the new manager of Oostende in the Belgian First Division A.[19]
On 19 January 2022, he was hired by Serie A club Genoa as the club's new head coach under a two-and-a-half-year contract, after the Italian club paid a fixed fee to activate a buyout clause present in Blessin's contract with Oostende.[22]
After failing to save Genoa from relegation, Blessin was confirmed in charge of the club for the 2022–23 Serie B season, with the goal to lead the Rossoblu promptly back to Serie A. On 6 December 2022, after a string of negative results, Blessin was dismissed from his role with immediate effect.[23][24]
^"COMUNICATO STAMPA". Genoa Cricket and Football Club (in Italian). 6 December 2022. Archived from the original on 6 December 2022. Retrieved 7 December 2022.