Guebuza was born in northern Mozambique. He joined FRELIMO at the age of 20, shortly after it began Mozambique’s war of independence against Portugal. By the time independence was achieved in 1975, Guebuza had become an important general and leader in FRELIMO. He became interior minister in the Samora Machel government and issued an order forcing certain Portuguese residents to leave within 24 hours, known as the “24 20” order because the residents in question were restricted to 20 kilograms of luggage. Following Machel’s death in a plane crash in South Africa, he was part of a committee investigating the circumstances of the crash, which came to no certain conclusion. He represented FRELIMO at the peace negotiations with the RENAMO guerilla group that led to the Rome General Peace Accords, signed in Rome on October 4, 1992. During the transitional phase towards the first general elections in 1994, he represented the Government of Mozambique in the joint Supervision and Monitoring Commission, the highest implementing body of the General Peace Accords.
Following the abandonment of socialist economic policies by President Joaquim Chissano, which included the privatization of state companies, Guebuza became a successful and wealthy businessman, particularly in the construction, exports and fishing industries.