Njarðvík is a town in southwestern Iceland, on the peninsula of Reykjanes. As of 2009, its population was 4,400.

In 1995 it merged with the town of Keflavík and the village of Hafnir to form the new municipality of Reykjanesbær.

Njarðvík is located in the Reykjanes region of Reykjavík, adjacent to Keflavík. It consists of two parts: Innri Njarðvík and Ytri Njarðvík (inner and outer Njarðvík). In the old town is the Njarðvíkurkirkja Innri, a stone church built in 1886.