Prefabricated slim floor systems represent a mature yet continuously evolving solution in multi-storey building construction. By integrating steel-concrete composite beams within the depth of the slab, these systems create a flat soffit, reduce structural depth, and enable efficient prefabrication-based construction processes. This paper provides an overview of prefabricated slim floors, focusing on their practical benefits and structural behavior. Attention is given to composite interaction between steel and concrete, the role of prefabricated elements such as hollow-core slabs, and the implications of Eurocode provisions. The paper highlights that slim floor systems are not only a structural innovation but also an important enabler of industrialized and adaptable construction.