Waikīkī is a neighborhood of Honolulu, in the City and County of Honolulu, on the south shore of the Island of O‘ahu, Hawai‘i. Waikīkī extends from the Ala Wai Canal (a channel dug to drain former wetlands) on the west and north, to Diamond Head or Leahi on the east. The name means fetched water in Hawaiian for springs that fed wetlands that once separated Waikīkī from the interior. Waikīkī has long been a place of relaxation. In particular, the area was a retreat for Hawaiian royalty in the 1800's.

Today it is considered the center of the tourist industry in Hawai‘i, with an abundance of both high-rise resort hotels (including the Hilton Hawaiian Village, the Hyatt Regency Waikiki, and the Sheraton Waikiki) and historic hotels dating back to the early 20th century (such as the Moana Surfrider Hotel and the Royal Hawaiian Hotel).

Waikīkī Beach is the shoreline fronting Waikīkī and one of the best known beaches in the world. The beach has had its problems, losing sand along many sections because of groynes built out from the shore. This has led to beach replenishment projects in the past, including a "disastrous" one involving a man-made sand that the gentle surf turned into a concrete-like surface.

Waikiki is also a suburb of Perth, Western Australia.