The United Malays National Organisation (UMNO; Malay: Pertubuhan Kebangsaan Melayu Bersatu, PEKEMBAR) is a conservative and Malay nationalist political party in Malaysia. Founded in 1946 by Onn Jaafar, it is the oldest national political party in the country and has been described as Malaysia's "Grand Old Party". UMNO is a founding and principal member of the Barisan Nasional (BN) coalition, which, together with its predecessor the Alliance Party, governed Malaysia from the independence of Malaya in 1957 until its defeat in the 2018 general election. During this period, every Prime Minister of Malaysia was also the President of UMNO.
Following the 2018 election, UMNO retained considerable influence in Malaysian politics. It returned to power twice during the 2020–2022 Malaysian political crisis, first as part of a Perikatan Nasional (PN)–led government and later as the leading party in a BN–led administration. In the latter, UMNO Vice President Ismail Sabri Yaakob served as Prime Minister from 2021 to 2022. Since 2022, the party’s president, Ahmad Zahid Hamidi, has served as Deputy Prime Minister of Malaysia in a Pakatan Harapan (PH)–led government. Despite changes in coalition alignments, UMNO continues to play a significant role in shaping national policy and political discourse.