Porkkalanniemi (Swedish: Porkala udd) is a peninsula in the Gulf of Finland, located at Kirkkonummi (Kyrkslätt) in Southern Finland.

The peninsula had great strategic value, as coastal artillery based there would be able to shoot more than halfway across the Gulf of Finland. If the same power controlled the Estonian coast, on the opposite side of the gulf, it would then be able to block Saint Petersburg's naval access to the Baltic Sea. The distance to Estonia at the closest point is only 36 km (22 mi). Porkkala is furthermore located only 30 kilometers (19 mi) from Helsinki, the Finnish capital, and a foreign power based there would be able to exert significant pressure on the Finnish government.

Nowadays, the coasts of the peninsula are popular birdwatching areas during the spring migrations of Arctic geese and other waterfowl.