Romaine Mundle received abuse online after the club's clash with Fulham on Sunday (February 23).
Sunderland AFC condemned what they described as "vile online racist abuse" directed towards the winger in a strong statement hours after the defeat against the Cottagers on Sunday where Mundle came off the bench for the Black Cats and missed a chance in the second half.
The 22-year-old was pictured looking devastated with his head in his hands after the game where it was revealed he had picked up an injury.
Northumbria Police has since said they are working with the Black Cats and the UK Football Policing Unit (UKFPU) as part of an investigation.
A force spokesperson said: “We have received a complaint about messages sent on social media.
“An investigation has now been launched and we are working alongside Sunderland AFC and the UK Football Policing Unit (UKFPU).
“We condemn all forms of discrimination – it has absolutely no place within society and our communities."
A club spokesperson added: "Sunderland AFC is appalled by the vile online racist abuse directed at Romaine Mundle following today’s Premier League fixture against Fulham.
"The abhorrent behaviour displayed by multiple individuals is unacceptable and will not be tolerated by the Club under any circumstances.
"There is no place for racism in our society, and we stand with Romaine, who has our full support.
"The Club is actively working with the relevant authorities and online platforms to identify those responsible, and we will take the strongest possible action available to us.
"These individuals do not represent Sunderland AFC, our values, or our community - and they are not welcome on Wearside."
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Mundle was not the only Premier League player to be the target of abuse over the weekend.
Wolves striker Tolu Arokodare faced an onslaught on Saturday followed by Chelsea’s Wesley Fofana and Burnley’s Hannibal Mejbri on Saturday.
Chief Constable Mark Roberts, the head of the UKFPU, said on Monday: “There is absolutely no place for racial abuse, either online or in person, and anyone who believes they can hide behind their keyboards should think again.
“The UKFPU condemns this abhorrent behaviour and we will ensure that, through our dedicated team of officers, we do everything possible to identify those responsible and bring them to justice.”