Unduk Ngadau Kaamatan is a beauty pageant held annually during the Kaamatan cultural event in Sabah, Malaysia.^[1] The reigning Unduk Ngadau Kaamatan is Carol Abbey Gail Grimaldi of Papar who was crowned by Unduk Ngadau Kaamatan 2022, Frenerietta Sobitun of Sandakan, on 31 May 2023 at KDCA Hall, Penampang, Sabah.

The Unduk Ngadau beauty pageant is held to commemorate the spirit of Huminodun, the mythological maiden who was of total beauty of the heart, mind and soul. The title is derived from the phrase runduk tadau which means "the girl crowned by the sunlight". Unduk Ngadau Kaamatan is one of the most recognizable cultural events in Sabah and is unique to the state. The state-level beauty pageant is the highlight and ending point of the month-long Kaamatan celebrations.

The contestants of the state-level beauty pageant generally represent their district. Some districts hold joint pageants, producing more than one representative.

Beginning in 1995, Sabahans residing in Peninsular Malaysia who celebrate Kaamatan have been acknowledged by the organization. Since then, many other states in Malaysia started to send their delegates to the pageant such as Johor in 2014, Penang in 2018, Putrajaya in 2019, Melaka and Perak in 2021. The first ever representative from Klang Valley was Angeline Ongkunik and the first Klang Valley's or Kuala Lumpur's representative who won the state-level crown was Daphne Iking in 2003. In the following year, Janeitha Stephen of Klang Valley was placed as the first runner-up to Tamparuli's Fharelynne Ivonne Henry. Many of the Klang Valley representatives have had their best placements in the state-level competition; 2001's Ryna Rychie James (second runner-up), 2005's Susanna James Kenson (fourth runner-up), 2007's Jaslinder Kaur (sixth runner-up), 2008's Anne Marie Tauriq Khan (sixth runner-up), 2013's Ledesma Steven (fifth runner-up), 2014's Maylesthelyn Ley Matius (sixth runner-up), 2016's Patricia Elsa Jimy (fifth runner-up), 2017's Sharlina Gilbert Mojinun (fifth runner-up) and 2019's Vinnie Alvionitta Sasising (sixth runner-up).

Since 2012, the question-and-answer round has been using the format through which the contestants must answer the question in their ethnic language. Melinda Louis was one of the first to have succeeded in the particular question-and-answer, and she eventually won.

In 2014, the state of Johor in Peninsular Malaysia made its debut in the competition. The first winner for Johor was Liz Lorena Rayner who was placed as the second runner-up in the competition. In 2023, the state of Sarawak joined the pageant for the first time. The first representative of Sarawak was Marylyn Velarie Bolovin.^[2]