The Uptown Funk and Valerie star was due to perform after racing at Doncaster Racecourse on July 1 - but the venue announced last night that the musician and producer was "unable to perform."
Brit Award winners Rudimental, whose hits include Not Giving In and Feel The Love, will now replace him.
A spokesman said: "We are excited to announce the Brit Award winning band Rudimental will perform at The Construction Index Race Day on Saturday 1 July at Doncaster Racecourse.
"Rudimental will take the place of Mark Ronson who is now unable to perform."
The band rose to prominence in 2012 when their single Feel the Love, featuring singer John Newman, topped the UK Singles Chart.
The following year, Rudimental’s debut studio album Home debuted at number one in the UK Albums Chart and was also nominated for a Mercury Music Prize.
Head of Marketing at Doncaster Racecourse, Abby Chandler, said “We are delighted that the multi- award winning Rudimental has agreed to step in and play Doncaster for the first time.
We look forward to a fantastic evening of racing and music on our Construction Index race evening and wish Mark Ronson all the best as he takes some time out from performing.”
Ticket details are available from Doncaster Racecourse.