The "No Problem" hitmaker was due to perform at the event in Dublin on Saturday 6 July, but has been forced to cancel the gig.
However, hip-hop fans won't be left too disappointed, as U.K. grime star Stormzy has agreed to fill in with his own headline set.
A tweet from Longitude organisers posted on Friday (June 21) read: "Unfortunately Chance The Rapper is no longer able to perform at #Longitude2019. We are delighted to announce that @Stormzy will headline the Saturday Night!!!"
The "Vossi Bop" rapper will take to the stage at the Irish capital's Marlay Park venue just a week after completing a headline set at England's Glastonbury festival.