Footage emerged on social media on Wednesday appearing to show Son being targeted with a racist gesture from the Stamford Bridge stands as he went over to take a corner in front of home fans.
In a statement released on its official website on Friday (AEST), Chelsea announced it is looking into the incident that took place in the second half of Sunday's eventful 2-2 draw with London rivals Spurs.
Club statement on racist abuse.— Chelsea FC (@ChelseaFC) August 18, 2022
"Chelsea Football Club finds any form of discriminatory behaviour totally abhorrent. It has no place at Chelsea or in any of our communities," the statement read.
"Chelsea FC has consistently made its zero tolerance position on discriminatory behaviour very clear, yet there are still idiots like this that attach themselves to this club as so-called 'fans', which shames Chelsea FC, our coaches, players, staff and our true supporters.
"We are investigating this incident and, if identified, this individual will face the strongest action from the club."
Spurs twice recovered from a goal down to rescue a point against Chelsea, with Harry Kane heading a stoppage-time equaliser in a game that saw head coaches Thomas Tuchel and Antonio Conte sent off after the full-time whistle.
Both managers have been charged by the Football Association, while Stats Perform understands the FA is looking into Tuchel's post-game comments about referee Anthony Taylor, whose performance the Chelsea boss criticised.