The 25-year-old tore two ligaments in his knee in during his side's 2-1 Bundesliga defeat by 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 second-tier club Heidenheim on Saturday and is keen to get more game time in the rest of pre-season, in search of full match fitness.
"My mind was everywhere," Subotic remarked to the media. "I wanted to help the team as well 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 enthused.
"He went into every tackle and was fully charged up."