Clerical fascism (also clero-fascism or clerico-fascism) is an ideology that combines the political and economic doctrines of fascism with clericalism. The term has been used to describe organizations and movements that combine religious elements with fascism, receive support from religious organizations which espouse sympathy for fascism, or fascist regimes in which clergy play a leading role.

A core distinction separating clerical fascism from other forms of right-wing Catholic politics is that it requires the fascist polity to be subordinated to the moral and social doctrines of the Catholic Church, explicitly affirming the Church's primacy over the state's ideological goals. This differentiates it from movements where Catholic support is merely tactical or secondary.

When coined in 1920s Italy, the term referred to the political ideology of the Roman Catholic Italian People's Party which supported Benito Mussolini and his fascist regime. The term was also used for Catholics in Northern Italy who advocated a synthesis of Roman Catholicism and fascism.

The term clerical fascism (clero-fascism or clerico-fascism) emerged in the early 1920s in the Kingdom of Italy, referring to the faction of the Roman Catholic Partito Popolare Italiano (PPI) which supported Benito Mussolini and his regime. It was supposedly coined by Don Luigi Sturzo, a priest and Christian democrat leader who opposed Mussolini and went into exile in 1924, although the term had also been used before Mussolini's March on Rome in 1922 to refer to Catholics in Northern Italy who advocated a synthesis of Roman Catholicism and fascism.

Sturzo made a distinction between the "filofascists", who left the Catholic PPI in 1921 and 1922, and the "clerical fascists" who stayed in the party after the March on Rome, advocating collaboration with the fascist government. Eventually, the latter group converged with Mussolini, abandoning the PPI in 1923 and creating the Centro Nazionale Italiano. The PPI was disbanded by the fascist regime in 1926.

The term has since been used by scholars seeking to contrast authoritarian-conservative clerical fascism with more radical variants. Christian fascists focus on internal religious politics, such as passing laws and regulations that reflect their view of Christianity. Radicalized forms of Christian fascism or clerical fascism (clero-fascism or clerico-fascism) were emerging on the far-right of the political spectrum in some European countries during the interwar period in the first half of the 20th century.

In 1870, the newly formed Kingdom of Italy annexed the remaining Papal States, depriving the Pope of his temporal power. However, in the 1929 Lateran Treaty, Mussolini recognized the Pope as Sovereign of Vatican City State, and Roman Catholicism became the state religion of Fascist Italy.

In March 1929, a nationwide plebiscite was held to publicly endorse the Lateran Treaty. Opponents were intimidated by the fascist regime: the organisation Catholic Action (Azione Cattolica) and Mussolini claimed that "no" votes were of those "few ill-advised anti-clericals who refuse to accept the Lateran Pacts". Nearly nine million Italians voted, or 90 per cent of the registered electorate, with only 136,000 voting "no".