The National United Front for an Independent, Neutral, Peaceful and Cooperative Cambodia, commonly referred to as FUNCINPEC, is a royalist political party in Cambodia. Founded in 1981 by Norodom Sihanouk, it began as a resistance movement against the People's Republic of Kampuchea (PRK) government. In 1982, it formed a resistance pact with the Coalition Government of Democratic Kampuchea (CGDK), together with the Khmer People's National Liberation Front (KPNLF) and the Khmer Rouge. It became a political party in 1992.

FUNCINPEC was one of the signatories of the 1991 Paris Peace Accords, which paved the way for the formation of the United Nations Transitional Authority in Cambodia (UNTAC). The party participated in the 1993 general elections organised by UNTAC. It won the elections, and formed a coalition government with the Cambodian People's Party (CPP), with which it jointly headed. Norodom Ranariddh, Sihanouk's son who had succeeded him as the party president, became First Prime Minister while Hun Sen, who was from the CPP, became Second Prime Minister.

In July 1997, violent clashes occurred between factional forces separately allied to FUNCINPEC and the CPP, leading to Ranariddh's ouster from his position as First Prime Minister. Ranariddh subsequently returned from exile in March 1998 and led the party to the 1998 general elections, which was won by CPP with FUNCINPEC as the first runner-up. Subsequently, FUNCINPEC joined CPP again, this time as a junior partner in a coalition government. Ranariddh was appointed as the President of the National Assembly, a post which he held until 2006 when he was ousted from FUNCINPEC by the party's former secretary-general Nhek Bun Chhay.

FUNCINPEC saw its share of voters and seats in the national assembly drop over the general elections of 2003, 2008 and 2013, with the party failing to win a single seat in the National Assembly at the 2013 general elections. In January 2015, Ranariddh returned to FUNCINPEC, and was reappointed as the party's president. The current acting president is Norodom Ranariddh's son, Prince Norodom Chakravuth.

"FUNCINPEC" is a French acronym for "Front uni national pour un Cambodge indépendant, neutre, pacifique, et coopératif", which translates as "National United Front for an Independent, Neutral, Peaceful, and Cooperative Cambodia" in English. It is commonly known by its acronym, used in the form of a word.

On 21 March 1981, Sihanouk founded FUNCINPEC, a royalist resistance movement, from Pyongyang, North Korea. Over the next few months, Sihanouk forged closer ties with the Chinese government as he saw the need of gathering resistance armies sympathetic to FUNCINPEC, such as MOULINAKA (Movement for the National Liberation of Kampuchea). He had resisted earlier attempts between 1979 till 1981 by the Chinese government for him to forge political alliances with the Khmer Rouge, whom he had accused of killing his own family members during the Cambodian genocide. He reconsidered his position over allying with the Khmer Rouge, with whom they shared a common goal of ousting the People's Republic of Kampuchea (PRK) government, which was under Vietnam's influence. In September 1981, Sihanouk met with Khmer People's National Liberation Front (KPNLF) leader Son Sann and Khmer Rouge leader Khieu Samphan to establish the framework for a coalition government-in-exile. Subsequently, on 22 June 1982, the Coalition Government of Democratic Kampuchea (CGDK) was formed, and Sihanouk was made its President.

In September 1982, Armee Nationale Sihanoukiste [ru] (ANS) was formed by the merger of several pro-FUNCINPEC resistance armies, including MOULINAKA. Ties between FUNCINPEC with the KPNLF and Khmer Rouge remained tenuous. On the one hand, Son Sann publicly criticised Sihanouk on several occasions, while on the other hand, the Khmer Rouge army periodically attacked the ANS, prompting Sihanouk in threatening to quit as CGDK's president on at least two occasions in June 1983 and July 1985. In December 1987, Sihanouk met with the Prime Minister of the PRK government, Hun Sen in France. The following year in July 1988, the first informal meeting was held in Jakarta, Indonesia between the four warring Cambodian factions consisting of FUNCINPEC, Khmer Rouge, KPNLF and the PRK government. The meetings were held with a view to end the Cambodian–Vietnamese War, and two additional meetings were later held which became known as the Jakarta Informal Meetings (JIM).

In August 1989, Sihanouk stepped down as the President of FUNCINPEC and was succeeded by Nhiek Tioulong. At the same time, Ranariddh was made the Secretary-General of the party. In September 1990, the four warring Cambodian factions reached an agreement to form the Supreme National Council (SNC), an organisation designed to oversee Cambodia's sovereign affairs in the United Nations on an interim basis. The SNC consisted of twelve members from the four warring Cambodian factions, with two seats going to FUNCINPEC. Sihanouk negotiated to become the 13th member of the SNC, a proposal which Hun Sen initially rejected, but later acceded after Sihanouk relinquished his FUNCINPEC party membership in July 1991. Sihanouk was elected as the chairman of the SNC, and the SNC seats under FUNCINPEC's quota were filled up by Ranariddh and Sam Rainsy. When the Paris Peace Accords were signed in October 1991, Ranariddh represented the party as its signatory.