The deal marks the Fire's fourth major trade in a month as the team tries to stay under MLS's budget guidelines. It has sent Josh Wolff to Kansas City, Dema Kovalenko to D.C. United and Peter Nowak to New England.
Stoitchkov, who was injured for much of his three-season stint in Chicago, scored 17 goals and 15 assists in 51 MLS games.
In 2000, his first MLS season, he helped the Fire to an MLS Cup runner-up finish and the U.S. Cup title.
Stoitchkov earned 84 caps and scored 37 goals for Bulgaria and helped the Bulgarians to a fourth-place finish at the 1994 World Cup.