After graduating, he became a doctor at Petrobras and began a specialization course in thoracic surgery at the National Tuberculosis Service in Rio de Janeiro, which he completed in 1958.

In 1975, he took courses in national security and development at the Associação dos Diplomados da Escola Superior de Guerra (ADESG) in Belém.

[1][4][5] In 1977, Almir Gabriel began his political career after being appointed director of the National Division of Sanitary Pneumology at the Ministry of Health, where he remained until 1979.

Sworn in on February 1, 1987, he was appointed by PMDB leader Mário Covas as rapporteur for the Social Order Commission, which dealt with issues related to workers' rights, health, security, the environment and minorities.

[1][6][8] During the debates in the Constituent Assembly, Almir Gabriel supported the rupture of diplomatic relations with countries that carried out policies of racial discrimination, the collective injunction, the 40-hour working week, the six-hour non-stop shift, proportional prior notice, the nationalization of the subsoil, the limitation of real interest rates to 12% per year, the prohibition of the blood trade, the creation of a fund to support agrarian reform and the expropriation of areas considered productive for the purposes of agrarian reform.

After the promulgation of the Constitution on October 5, 1988, he resumed his regular legislative work in the Senate, serving as general rapporteur of the Joint Budget Committee in the same year.

[1] In 1989, he joined the Brazilian Social Democracy Party (PSDB), an organization formed in June of the previous year as a result of the discontent of some parliamentarians with the outcome of the Constituent Assembly votes.

[1][14] After four years out of public life, Almir Gabriel ran again for the government of Pará in the 2006 elections, with Valéria Pires Franco as his vice-governor candidate.

Although he was never held formally responsible for what happened, Almir Gabriel was identified by the Landless Workers' Movement (MST) as the mastermind, since he allegedly ordered the road to be cleared by violent force.