The northern French club said on Aug. 1 that the 35-year-old Yılmaz has signed a two-year deal.
He twice finished top scorer in the Turkish Süper Lig with former club Galatasaray and has more than 200 goals at club level in
Turkey, including 23 in 25 games with Trabzonspor in the 2017-18 season. He has netted 24 times in 59 appearances for the national side.
Lille sold the highly rated Osimhen to the Italian side on Friday in a deal reportedly worth around 80 million euros ($94 million) with bonuses included.
Lille is reuniting Yılmaz with attacking midfielder Yusuf Yazıcı, who set up many of his goals at Trabzonspor.
Hurriyet Daily News