The 26-year-old is reported to be signing a five-year contract at Selhurst Park after earning 5 goals and 5 assists in 35 appearances for the French club last season.
The Senegal star won the Africa Cup of Nations in 2021 and has 13 goals in 64 caps for his national side in what has been an impressive few years for the winger.
Palace have been desperately searching for a replacement for Michael Olise since the Frenchman joined Bayern Munich this window and Sarr could be the man to replace him.
Olise joined the German side for £50M and if Sarr does leave for a fee of around £12 then that leaves Palace with an extra boost in their budget to bring in more talent.
The club have already signed Daichi Kamada and Chadi Riad this summer and will look to attract more players in what could be a European qualification fight for the club.