Lincoln are entitled to compensation for the player as he is under the age of 24, but that has yet to be agreed.
Foxes boss Nigel Pearson has been tracking N'Guessan since the end of the season and he was delighted to finally get his man.
He said: "Dany is an extremely exciting prospect. He impressed us during our home game against Lincoln in the Johnstone's Paint Trophy last season and he is a versatile and talented player.
"He is an attacking player by nature. He can play on the left, right or up front, or even just behind the strikers.
"We are certain that the addition of Dany will heighten competition for places and he has the potential to improve."