Both players join the club as free agents and have signed two-and-a-half-year contracts with the Scottish side.
Killie boss Mixu Paatelainen said: “Billy Berntsson is a full-back who is very positive and he gives us cover in the defensive area, on the right and left-hand sides.
“We’ve also added another player to the squad, Benjamin Laurant, a French midfielder.
“We feel he is a skilful player who can make things happen and also give us plenty of cover for the midfield positions.”
