Austin is the second player in Scottish football to report such abuse in consecutive weekends. Airdrie launched an investigation into a complaint by their player Rico Quitongo.
Former East Fife and Inverness striker Austin netted a hat-trick in Kelty's 3-0 win at Cliftonhill but admitted the incident had soured the occasion.
Writing on his Twitter account and publishing a photograph of the signed match ball, Austin said: "A Perfect hat-trick tarnished by an Albion fan calling me a m but I guess that's the world we live in. enjoy your Saturday folks cos I will."
A Rovers fan group quickly apologised to Austin and distanced themselves from the perpetrator.
In a statement on Twitter, the Coatbridge Boys group wrote: "Today one of Kelty Hearts players Nathan Austin was racially abused by a member of our group, since then the person has owned up to it and has been removed from our group, we would (like) to apologise to Nathan and Kelty Hearts, Coatbridge Boys stand against racism."
Kelty Hearts later issued a statement of their own in response to the abuse.
The statement read: "We are aware of an incident of racist abuse during our match against Albion Rovers FC today. It came from an individual in the home end terracing towards one of our players.
"An investigation is underway with our friends from Albion Rovers FC, who gave all at our club a fantastic welcome on our first visit to Cliftonhill.
"Kelty Hearts Football Club shall support all our players and members fully against racism of any kind, we strongly condemn racism and are totally committed to the elimination of all forms of discrimination."
Albion Rovers have been approached for comment.
Days earlier Quitongo reported being subjected to racial abuse by one of his own supporters during Airdrie's game against Queen's Park. Airdrie launched an investigation and gave Quitongo their full support.