A baby safety car seat convertible into a rollable baby seat, and comprising a front, head area and a rear, feet area, the head area being higher than the feet area; a right and left pair of front and rear legs, and a handle. The legs of each pair have distal ends associated with wheels and proximal ends articulated to the seat at corresponding leg attachment area. Both legs are rotatable relative to each other and to the seat between a storage position to be taken in a safety car seat mode of the seat, and an operational position to be taken in a rolling-carrier mode of the seat. The legs can have an intermediate position between the storage and operational position, and can be rotatable between the intermediate and operational positions, at least partially under the influence of gravity force.