The incident happened in a pre-season friendly last July between Wednesday and Mansfield, with Forestieri’s comments made towards Mansfield defender Krystian Pearce sparking a brawl on the pitch.
Forestieri was acquitted by magistrates in March of racially abusing Pearce but was charged by the Football Association in June.
The commission deemed the case against Forestieri proven, and the 29-year-old has also been given a £25,000 ($31,000) fine, warned as to his future conduct and ordered to attend face-to-face education.
Forestieri immediately announced he would be appealing, saying he was “devastated and disappointed” by the outcome.
In a statement on Wednesday’s official website, he said: “I have now been the subject of allegations of racism for over a year and it has been an extremely stressful time for both me personally and also my family in both England and Argentina.”
Forestieri continued to protest his innocence, saying: “I am not and never will be a person or a footballer who says offensive things by reference to race to my colleagues or other players, either on or off the pitch.”