Balde has been strongly linked with a move this summer, with Juventus having had an offer rejected.
But according to Get French Football, a deal has been concluded with Lazio for the transfer of the Senegalese international.
The report further suggests that Balde has arrived in Monaco where he will undergo a medical ahead of a €30 million -plus bonuses- move, before signing a five-year contract
The versatile attacker’s contract at the capital side is to expire next summer and Lazio are keen to sell.
Monaco are expected to make tons from the sale of Kylian Mbappe to Paris Saint-Germain and are willing to offer the amount Lazio wants for the 22-year-old.
Keita enjoyed a breakout campaign in the Italian top flight last season as he notched 16 goals and 3 assists in 35 appearances for Lazio.