Martínez Camps was born in Santiago on 13 September 1909, the son of Juan Martínez Vásquez and María Camps Márquez. He married Julia Esteban A., with whom he had four children, and later married María Consuelo Saavedra Jarpa, with whom he had two more.
He studied at Public School No. 9 in Santiago and later at the Liceo and the Instituto Superior de Comercio of Valparaíso, graduating as an accountant in 1929 with the thesis "Public Accounting."
He joined the Radical Party of Chile, where he held various responsibilities: president of the Radical Assembly of the Ninth Commune of Santiago; delegate to conventions; provincial delegate and national leader; and member of the Supreme Tribunal.
In 1930 he began working as an assistant accountant in the Ministry of Agriculture, and between 1942 and 1947 he was chief accountant of the Department of Oenology and Viticulture.
Between 1947 and 1952 he served as councilman of Santiago, representing the municipality before the Council of Municipal Employees and Workers Fund, as Chilean delegate to the Inter-American Congress of Municipalities, and as president of the Legal Affairs and Finance Commissions of the Municipality of Santiago.
In 1953 he was elected deputy for the 7th Departmental District of Santiago, serving the 1953–1957 legislative period. He was a member of the Permanent Committee on Internal Government and of the Economy and Commerce Committee.
In 1957 he was re-elected deputy for 1957–1961, and again in 1961 for 1961–1965. During this period, he was a member of the Permanent Committee on Foreign Relations. In August 1961, he traveled to China with his wife and deputy Raúl Juliet, meeting with Prime Minister Zhou Enlai on 6 August in Beijing.
In 1965 he was re-elected deputy for the 1965–1969 term, serving again on the Permanent Committee on Foreign Relations.
At various times, he also participated in the Special Committee on Housing for Municipal Employees and Workers, which he chaired.
In 1971, as a leader of the Chilean-Chinese Institute of Culture, he traveled again to the People's Republic of China and met once more with Premier Zhou Enlai on 29 August.
In the early 1970s, he joined the Radical Left Party, and during the transition to democracy in 1989, he joined the Chilean Social Democracy Party, becoming a member of its first executive board. This group later merged with the Radical Party to form the Radical Social Democratic Party.
Martínez Camps died in Santiago on 25 September 1998.