Kariotahi Beach, Black sand beach in Auckland region, New Zealand

Kariotahi Beach is a black sand beach on the west coast of New Zealand's North Island, located south of Auckland. The sand runs along a line of natural dunes that separate the shore from the low hills behind.

The name Kariotahi comes from the Maori language and has long been tied to this stretch of coastline. The current spelling was formally recorded in 1950, during a wider effort to standardize place names across New Zealand.

The local surf club, founded in 1969 as Kariaotahi Surf Life Saving Patrol Inc and renamed Surf Life Saving Kariaotahi Inc in 2006, patrols the beach on weekends and public holidays from Labour Weekend in October to March or early April. Its lifeguards compete in canoe and IRB racing, and the club adopted red, white and black colours to match Counties Manukau teams.

Patrolled weekends and public holidays from Labour Weekend in October to March or early April, with hours of 11:00–16:00 in October, November, March and April and 11:00–17:00 in December, January and February. Weekday patrols run 10:00–18:00 from mid-December to late January. The beach is about 8 km from Waiuku, and the southern end at Maioro is used by paragliding schools for beginner training.

The southern end of the beach and its cliff, called Maioro, is used by local paragliding schools to train beginners. Qualified pilots are advised against flying there, which keeps the air clear for learners. The beach's iron oxide sand was eroded from Mount Taranaki and carried north along the Waikato River.