Nikaia (Greek: Νίκαια, before 1940: Νέα Κοκκινιά - Nea Kokkinia) is a suburb in the western part of the Athens-Piraeus agglomeration, Greece. Since the 2011 local government reform it is part of the municipality Nikaia-Agios Ioannis Rentis, of which it is the seat and a municipal unit.
Nikaia, like many other places around Greece, owes its population eruption to Greek refugees who left the Asia Minor coast after the 1922 war ended. It was part of the municipality of Piraeus until 1933, when it became a separate municipality, then still under the name Nea Kokkinia. It was renamed to Nikaia in 1940.
The 8th International Tournament of Nikaia, a chess tournament, took place between August 19 and 27, 2000. The Greek Weightlifting Grand Prix took place in Nikaia on December 9 and 10, 2003.