Maíno was born in Pastrana, a Spanish town in the province of Guadalajara approximately 80km from Madrid, known for its silk trade and production.
The son of a Portuguese mother and a Milanese cloth merchant, Maíno may have received his artistic training in Madrid before travelling to Italy as a young man. He is thought to have travelled through Lombardy and visited Genoa and Naples.
In 1609/10 he is recorded as living in the parish of Sant’Andrea delle Fratte in Rome. The date of his arrival in the city is unknown but he was certainly there by at least 1604, for it was in Rome that his son Francesco was baptised on 17 October 1605 (though no further references to either his son or to the boy’s mother have been found).
By 1611 Maíno had returned to Spain and on 14 February 1612 he signed a contract to execute the paintings for a vast 'retablo' (altarpiece) for the high altar of the church in the Dominican house of San Pedro Mártir, Toledo. Before completing the commission Maíno took religious vows, joining the Dominican Order on 27 July 1613 (thus his title ‘Fray’ meaning Brother).
In around 1616 Maíno moved to Madrid where he became master of painting to Prince Philip (later Philip IV). Maíno took an active part in the court’s artistic life: in 1627 he was among those who awarded first place to Velázquez in a competition, and in 1634–5 Maíno painted his masterpiece, 'The Recapture of Bahía' (Museo Nacional del Prado, Madrid), for the Hall of Realms in the Royal Buen Retiro Palace.
Despite a long and successful career, surprisingly few works by Maíno are known. In addition to working on a large scale, he was adept at painting on small copper panels and contemporaries considered him a gifted portraitist.
Maíno’s paintings reveal his knowledge of the stylistic tendencies prevalent in early 17th-century Rome: they combine the naturalism of Caravaggio with the refined palette of Gentileschi, as well as the more classicising style of Carracci and Reni, both of whom Maíno knew personally.