The Ligue 1 champions are understood to have paid around €30m (£27.8m) for the 22-year-old, who had rejected a number of other clubs during the current transfer window.
AS Monaco complete signing of Keita Balde Diao
AS Monaco complete the signing of 22-year-old forward Keita Balde Diao on a five-year deal from Lazio.
Monaco 'agree fee with Lazio for Keita'>
You May Like
Recomended from Sports Mole
Follow @SMMonaco to get every Monaco headline from Sports Mole, and follow @SportsMole for the latest breaking news stories