Ifill was the subject of a "blatantly racist" remark from a fan behind the Phoenix bench after he was substituted in his side's 3-1 defeat to the Reds last weekend.
The Phoenix reported the incident to match officials who contacted South Australian police to investigate the matter. The man has now been identified and FFA today announced he would be prohibited from attending any match under their jurisdiction for two years.
In addition to the sanction, Adelaide United have simultaneously cancelled the man's club membership.
Phoenix general manager David Dome said the club were satisfied with the outcome.
"We are happy that the process has been followed and we put our faith in Adelaide United, the South Australian police and the FFA, and they've obviously done a fantastic job finding the guy and they've banned him appropriately.
"So we are pleased that the process has been followed and it's worked out well."
The case was believed to be the first incident of racism in the A-League, but the punishment is in line with similar sanctions handed to fans found guilty of racial offences at football matches in Europe.
Ifill, an English-born Barbados international, took to Twitter after the match complaining of abuse from a "very small minority" of fans.
"Not happy been a long time since IV had to deal with anything like that," he wrote. "A few things that were blatantly racist that I'd rather not repeat."
Adelaide United conveyed their concerns to Ifill, and the Phoenix said they had accepted an "unequivocal apology".
