An angry Bent has used his Twitter feed to make his feelings known after the Wearsiders' 1-0 defeat at the DW Stadium.
He said: "So we get beaten by Wigan and my mum gets racially abused by a Sunderland fan."
The England striker says it was an "absolute disgrace" and added: "I won't stand for that."
Bent later Tweeted: "The offender needs to hope I don't find out his name or who he is".
Police are said to be investigating the allegation.
A Sunderland spokeswoman said: "Sunderland are liaising with Northumbria Police to fully investigate this matter."And added: "Behaviour of this kind is totally unacceptable to our football club."
Greater Manchester Police have also appealed for witnesses to come forward as they also launched an investigation into the report of racial abuse.
They want witnesses to call 0161 872 5050.