Reykjanesviti (Icelandic pronunciation: [ˈreiːcaˌnɛːsˌvɪːtɪ]) is Iceland's oldest lighthouse, located at Reykjanestá. It serves as a landfall light for Reykjavík and Keflavík.

The tower is a 31 metres (102 ft) tall construction, situated on the southwestern edge of the Reykjanes peninsula. The original structure was built in 1878; just eight years later the building was destroyed by an earthquake. In 1929 the current Reykjanesviti lighthouse, a concrete construction yet with traditional looks, was illuminated. Its focal plane measures 73 metres above sea level.

The light characteristic is "Fl (2) W 30 s.", i.e. a group of two flashing lights every 30 seconds. An antenna for the transmission of DGPS-signals in the longwave range is mounted on the rooftop. There is also a two-story keeper's residence built in the modern area, and the lighthouse has a resident keeper. The lighthouse is located near an area of thermal activity, and steam from this source is often seen in photographs of the lighthouse.

• List of lighthouses in Iceland

• Heimasíða Siglingastofnunar Íslands –Reykjanesviti (in Icelandic)