He also spent two seasons in the USL Premier Development League, playing for Michigan Bucks in 2004 and Kalamazoo Kingdom in 2005.

Peterson scored his first goal for Toronto in the CONCACAF Champions League group stage versusReal Salt Lake in a 1–1 home draw on September 28.

After a disappointing first half of 2011, Peterson was traded along with Alan Gordon and Nana Attakora to San Jose Earthquakes for Ryan Johnson, allocation money, and an international roster spot.

[4] He would play five seasons with Sporting KC and was part of the 2013 MLS Cup winners and two Lamar Hunt U.S. Open Cup-winning squads.

During his time with Sporting, he became known for his hard work and versatility, garnering the nickname "The Answer" for his ability to fill in at multiple positions.