The former Hearts player said he was "truly sorry" to be leaving Easter Road and thanked manager Mixu Paatelainen for all his support during his time at the club.
"I have had a wonderful time at Hibernian and have a great relationship with the manager (Mixu Paatelainen)," Park told the Hibernian club official website.
"I am truly sorry to be leaving him, the coaching staff, players and a fantastic training centre."
Paatelainen added: "I would like to thank Donald for his input throughout the last 18 months.
"Donald is very enthusiastic and has helped coaches and players alike.
"Everyone would like to wish Donald well for the new challenge he faces. I have no hesitation in saying he will do a good job for the SFA."