The defender has spent the last eight months on the sidelines after suffering a knee cruciate ligament injury in a 2-1 defeat against Wolfsburg in November.
Subotic had shown positive signs in his rehabilitation that lifted hopes he may return before the end of last season, but he did not recover in time to be considered by Jurgen Klopp.
With Dortmund set to open their Bundesliga campaign against Bayer Leverkusen on August 23 the defender could now provide a welcome boost to his head coach after giving an update on his progress via Facebook.
In a post on his official page the 25-year-old revealed he had taken the first step in returning to action, he wrote: "After my eight-month injury break, today I got to train with my team."
Subotic, a Serbia international, was part of the successful Dortmund side that won back-to-back league titles in 2011 and 2012 having formed a solid partnership with central defensive partner Mats Hummels.
