The population increased substantially after World War II, when many people from Southern Italy settled here (especially from Apulia).

After being subject for a long time to the influence exerted by San Maurizio al Lambro (which is now part of the municipality as a hamlet) Cologno received the honorary title of city with a presidential decree on September 19, 1996.

Sights in Cologno include Villa Casati, the seat of the comune, and San Giuliano, a medieval Romanesque church.

Part of the commune is included in the Media Valle del Lambro Park.

Cologno is also linked up with Milan by the Tangenziale Est, an orbital motorway that surrounds the capital city of Lombardy.