Emilio Guinea López earned his doctorate at Complutense University of Madrid in 1932. He obtained the chair of Natural Sciences at a secondary school and combined this teaching job with botanical research. He joined the botany section of the Institute of African Studies of the Higher Scientific research Council (CSIC) in 1949 and became head of that section in 1952.

Guinea López became curator of the Royal Botanical Garden of Madrid in 1957. He was appointed associate professor of the Antonio José de Cavanilles Botanical Institute of the CSIC in 1959. He held the position of head of the Tropical Flora section in 1962 and the European Flora section in 1968 at the same institution.

He made many trips to tropical Africa in the 1940s and 1950s, especially to equatorial Guinea and the North Africa deserts, performing geobotanical and taxonomic work.

He was a member of the Advisory Committee of the Flora Europaea project. He was also a skilled scientific illustrator, and in 1968 was invited to participate in the First International exhibition of Botanical Art and Illustration at the Hunt Institute for Botanical Documentation.

His personal library, archive and herbarium were donated to the Madrid Botanical Garden, where he served as honorary director.