2013: On January 31, Dimitrov signed with the New York Cosmos for their inaugural season in the NASL. The Strikers announced they acquired Dimitrov on loan for the Spring season on March 8.

Dimitrov made his first appearance for the Strikers in the season opener on April 6, starting and playing the full 90 minutes in the 1-1 draw with FC Edmonton.

Professional: Dimitrov was signed by Chicago Fire in March 2009, after being invited to try out with the team by head coach Denis Hamlett. He made his MLS debut on 13 June 2009, as a late substitute in a game against D.C. United. He appeared in seven games, starting one, and totaling 124 minutes in his first year as a professional for the Fire. He played 45 minutes against Club America on April 29, notching an assist in the 73rd minute of play.

Dimitrov was released by Chicago on August 27, 2010. He played for the New York Pancyprian-Freedoms in the US Open Cup in 2011, before signing for New York Cosmos U-23 in 2011 and was selected as one of the U-23 players to participate in the Paul Scholes testimonial match between the New York Cosmos and Manchester United.

College: Playing for the Concordia College Clippers in New York, Stefan finished first in goals and goals per game in the NCAA Division II Men's Soccer regular season in 2008. Stefan scored 23 goals and 1 assist in 17 games for a total of 47 points and 2.76 points-per-game average. He scored multiple goals in 7 games that season and scored at least one goal in 13 of 17 games for Concordia in 2008. Voted to the 2008 Daktronics NCAA Division II Men's Soccer All-America Second Team and named the 2008 East Coast Conference Offensive Player of the Year.

Participated in the 1st Annual Newark Ironbound Express College Soccer Showcase at the New York Institute of Technology in Newark, NJ on Saturday, November 29, 2008 and scored two goals and two assists in picking up MVP honors for the game.

Personal: Stefan speaks 3 languages: English, Bulgarian and Russian. He attended high school in Bulgaria and after high school attended the national sports academy, Vasil levski Sofia, for three semesters. His parents are Ivan and Yuliya and he has a bother named Dimitar.