20th Century Spanish
 
Born in Madrid, Mignoni was the son of the Italian scenographer Fernando Mignoni Monticelli and the Flamenco dancer Carmen Guerra. He therefore spent the early days of his life in an artistic environment, something that encouraged the young Mignoni to enrol at the San Fernando School of Fine Arts and the Círculo de Bellas Artes, both in Madrid, where he came into contact with some of the great artists of the time, such as Daniel Vázquez Díaz (1882-1969).

In 1958, eight years after he started his training, he had his first solo exhibition at Ateneo de Madrid.

In the 1960s he moved to Paris and his practice underwent a major change which is most noticeable in the greater focus on colour.

In 1967 he founded Galería Theo, which he ran personally together with his wife, Elvira González.