A member of the Kongo ethnic group, Kasa-Vubu became the leader of the Alliance des Bakongo (ABAKO) party in the 1950s and soon became a leading proponent of Congo's independence from Belgian colonial rule.

During this time, Kasa-Vubu, a centrist, clashed with the leftist Lumumba when the latter ordered assistance from the Soviet Union, leading to a political deadlock.

His father was a successful farmer who, as an independent entrepreneur, traded with street merchants in Cabinda and built his house at the outskirts of the village.

This earned him the animosity of the villagers and in an attempt to assuage their hostility he volunteered to undergo a "poison test" with a substance extracted from a kasa tree.

Dissatisfied with his salary of 80 francs per month, Kasa-Vubu passed the instructor's exam and became a sixth-grade teacher at the mission school in early 1941.

With a monthly pay of 500 francs, he felt financially secure enough to marry; on 10 October Kasa-Vubu wedded Hortense Ngoma Masunda in a Catholic ceremony at the Kangu mission.

[4] In June 1942 Kasa-Vubu earned a job as a clerk in the finance department of the Belgian colonial administration in Léopoldville, the capital of the Congo.

He worked there for 15 years,[4] attaining the rank of chief clerk, the highest level of employment available to Congolese civil servants under Belgian rule.

[7] In his inauguration speech as mayor of Dendale, Kasa-Vubu reiterated his demand for independence, drawing a reprimand from Belgian colonial authorities, which only strengthened his image as a Congolese leader.

[5] On 4 January 1959, an ABAKO political gathering organised by Kasa-Vubu erupted into violence, sparking the Léopoldville riots, a pivotal moment in the Congolese struggle for independence.

In a political compromise, it was agreed that Patrice Lumumba, of the Mouvement National Congolais (MNC) would be prime minister, and Kasa-Vubu would face Jean Bolikango, a former mentor in the ABAKO, for the presidency.

The Belgian press reacted positively to the development, while the Léopoldville's daily newspaper Courrier d'Afrique, edited by a Kongo, showed much warmer approval of the government.

[12] The new republic was immediately disrupted by political and military strife and regional secessionist movements, and the central government was paralyzed by conflict between the conservative Kasa-Vubu and leftist Prime Minister Lumumba.

[7] Kasa-Vubu was regarded as rather mysterious in his motivations and his actions, frequently preferring to stay silent or give ambiguous answers when he was confronted.

During the immediate upheaval following independence, Kasa-Vubu took few steps and made few definitive statements, even as Lumumba appealed for international assistance to the Americans, the United Nations and the Soviet Union.

[18] Anthropologist Yolanda Covington-Ward wrote that, contrary to Lumumba's "privileged" position in historiography on Congolese nationalism, Kasa-Vubu and ABAKO were the primary "driving force" behind the independence movement.