The fan was allegedly sitting in the home section at Old Trafford with the police informed about the incident.
“We are aware of an incident at yesterday’s game where an individual in the home section has allegedly engaged in racial abuse,” said a United club spokesman.
“The individual was identified and ejected from the stadium. We are currently investigating the matter as a priority.
“Racism and all forms of discrimination are completely unacceptable and do not reflect the values of our club.”
The incident occurred in the same weekend that Haringey Borough players walked off the pitch against Yeovil Town in their FA Cup tie following alleged racist abuse.