The Serbia international had been out of action due to a knee injury ever since November 2013 but came on as a late substitute against Heidenheim in Saturday's friendly
Subotic, 25, tore two ligaments in his knee in the Bundesliga in the 2-1 defeat against Wolfsburg in November and was consequently ruled out for the rest of the 2013-14 season.
After more than eight months on the sidelines, Subotic came on with 15 minutes remaining in Dortmund's 4-3 friendly win over 2.Bundesliga side Heidenheim on Saturday.
The Serbia international was delighted to be back and hopes to get more game time in pre-season as he looks to regain match fitness.
"My mind was everywhere," Subotic said. "I wanted to help the team as good as possible, but I have to get accustomed again to play against opponents hurling themselves into tackles.
"It's impossible to create this competitive environment in training. It's a great feeling to be back. It was great fun and I hope I get the opportunity to play a full half in the next game."
Dortmund coach Jurgen Klopp, meanwhile, was thrilled to see the centre-back still unafraid to make tough challenges.
"He was grinning like a Cheshire cat and was immediately in the thick of action. That's Neven," he said.
"He went into every tackle and was fully charged up."