Buylla's father was a diplomat who fled to South America due to Spanish political reprisals. Buylla returned to Spain in 1948.

He is most known for the science fiction adventurer, Commander Diego Valor, which he drew in collaboration with Braulio Rodriguez (Bayo) from 1954 to 1956, and then solo from 1957 to 1958, with scripts by Jarber. The character was adapted for radio, theatre and television.

Around 1956, he also did art for Víctor Mora's scripts on the classic Spanish series El Capitán, Trueno (Editorial Bruguera).

Through the 1960s to 1980s, Buylla predominantly drew for the international market. In the US, he had work published by Marvel, DC, Western (Gold Key), Pacific Comics, Renegade Press, Charlton and Warren. In the UK, he contributed to 2000 AD and Marvel UK titles such as Doctor Who.

In 1992, Buylla received the award of 'Al Autor que Amamos' (the author we love) at the Salón del Cómic del Principado de Asturias in Gijón, and was celebrated with an exhibition of 70 of his originals works. The Museo de Bellas Artes de Asturias did a retrospective of his work in 2001.