Juan Antonio Ríos Morales (Latin American Spanish: [xwan anˈtonjo ˈri.os]; November 10, 1888 – June 27, 1946) was a Chilean political figure who served as president of Chile from 1942 to 1946, during the height of World War II.

During the Aguirre Cerda administration, Ríos was president of Chile's largest bank, the state-owned Caja de Credito Hipotecario, which made mortgage loans to Chilean farmers.

In 1941, due to his rapidly escalating illness, President Aguirre Cerda appointed his minister of the Interior, Jerónimo Méndez as vice-president and died soon after, on November 25, 1941.

The results were too close to call, so a tribunal of honor (electoral commission) was constituted, and Juan Antonio Ríos was finally proclaimed the candidate of the left-wings' coalition.

Ríos' presidency was marked from the very beginning by parliamentary instability, caused by rivalries between the different political tendencies in his cabinet, and the renewed and increased influence of Congress.

The Chilean Communist Party opposed Ríos because he had initially chosen neutrality in World War II and had refused to break off diplomatic relations with the Axis Powers, while the right-wing accused him of complacency with the left.

Economically, he faced labor unrest at home, brought about in large part by a drop in copper prices worldwide, while at the same time, the Chilean Socialist Party accused him of being too soft with big business and of failing to enact labour legislation protecting workers' rights.

Ríos' option instead was to appoint "technical experts" and "personal friends" to cabinet and high-level government positions; this policy allowed him to include not only members of his own party, but also from the Conservative and Liberal opposition.

After his return from the United States, and faced with failing health, he transferred his presidential powers to his minister of the Interior Alfredo Duhalde (January 17, 1946) and died of cancer roughly 6 months later, on June 27.

Ríos' administration — continuing the Aguirre Cerda policies — focused on the development of the steel, power and oil industries.

Up to 1943, Chile and Argentina had declined to sever relations with the Axis powers, and the Chilean election was viewed by many as critical during World War II.

Initially, Ríos' government was committed to neutrality during the war, but the left-wing parties of his coalition were in favor of an immediate and total rupture with the Axis as well as for the recognition of the USSR, which they saw as their contribution to the world-struggle against fascism.

Juan Antonio Ríos spent his last days at Villa Paidahue, in La Reina, where he died on June 27, 1946, before the end of his constitutional period.