On April 30, 2022, Stefanovic made his professional debut with Toronto FC II in MLS Next Pro against FC Cincinnati 2, as an academy call-up.[1] On June 30, 2023, he signed an official professional contract with Toronto FC II, after having already played 13 games that season as an academy call-up.[1] The next day, he joined the Toronto FC first team on a short-term loan,[5] making his Major League Soccer debut that day in a substitute appearance in a 1–0 loss to Real Salt Lake.[6][7] He became the second-youngest player to appear in an MLS match for Toronto FC (16 years, 10 months and 22 days).[8] He signed another short-term loan ahead of a Leagues Cup match against Mexican club Atlas.[9][10] He joined the first team for their 2024 preseason training camp.[11] He missed much of the 2024 season due to injury from a broken bone, suffered while on international duty.[12]
After initially signing as an off-roster player earlier, he would officially join the Toronto FC first team roster for the 2025 season.[12]
International career
Stefanovic is of Serbian descent, born in the United States, and raised in Canada, and eligible for all three nations at international level.[13]
In August 2022, Stefanovic was called up to a training camp for the United States U17 team.[14]