A contactless braking system and a related method for decelerating long products (bi) exiting from a rolling mill (100). At least one braking module (6) includes a multiplicity of electromagnets (60) in a series along a braking line (1b). Each magnet has an open magnetic core (61) and a coil (62) around the magnetic core (61). The open magnetic core (61) has a gap formed by two opposed poles. The electromagnets (60) are configured so that the gap of each open magnetic core (61) lets contactlessly slide therethrough each long product (bi) exiting from the rolling mill (100). A braking magnetic force (Fd) is exerted on the long product (bi) contactlessly sliding through the gap. The braking magnetic force (Fd) is opposite to the direction of movement of the long product (bi) exiting the rolling mill (100).