He took a degree in Law at Oviedo University and became a journalist in 1959. Manuel Sarmiento started his journalistic activity in the Asturian newspaper Region and then he wrote articles for La Voz de Asturias and La Nueva España. Besides, he collaborated in El Noticiario Universal (Barcelona), La Voz de Galicia and La Voz de Madrid. In 1965, he was nominated as sports editor in the newspaper Informaciones (Madrid) but he spent the most part of his journalistic career in the newspaper As (he was a foundation member of this newspaper and became editor-in-chief in 1967). In 1975, he was nominated as assistant editor of this newspaper. He also collaborated in the TV programme 'Cabalgata de fin de semana'.