The victim suffered stab wounds after being approached by two men outside the centre in St Sepulchre Gate.
The incident too k place on February 9, but details have only just been released.
It is the latest in a long line of knife and gun incidents in Doncaster in the last 12 months.
A South Yorkshire Police spokesman said: "We received a call at 12:46pm on 9 February for reports of a stabbing at Frenchgate, Doncaster.
"It is alleged that two men have approached a believed to be known man outside the Poundshop store and stabbed him.
"The victim and the men left the scene. Enquiries are on-going and an investigation is underway.
"Anyone with information is asked to call 101 quoting incident number 431 of 9 February."