The move puts to bed speculation regarding the player's future as he has apparently signed a three-year deal and will link up with his new teammates upon their return from Togo.
Sundowns are currently out of the country as they honour their Caf Champions League assignment against Togo-Port on Tuesday.
Although, previous reports suggested that the Mother City-born player was on the wanted list of Bidvest Wits, coach Pitso Mosimane has won the battle for the player's signature.
"Yes, Lakay has signed for Sundowns on a three-year deal," the source told Goal on Sunday.
The player has completed his switch after undergoing a medical test at Chloorkop and an official announcement of 26-year-old's signing is believed to be imminent.
Moreover, Lakay joins the likes of Andile Jali, Toni Silva, and Jose Ali Meza who have all signed with the club in the current transfer window.
Lakay could compete against the likes of Aubrey Ngoma for a spot on the left flank, but reports also suggested that he could be converted into a left-back where he will fight for a place in the starting line-up against the likes of Tebogo langerman and Siyabonga Zulu.
Meanwhile, the creative winger could be unleashed on Saturday when the 2016 African champions face Kaizer Chiefs in the inaugural Shell Helix Cup at FNB Stadium.