Nicolau Nasoni was born in San Giovanni Valdarno di Sopra, in Tuscany, on 2 June 1691. He was the eldest of two sons of Giuseppe Francesco Nasoni and Margaretta Rossi.
In Siena, he began his artistic learning and professional activity in the field of ephemeral art (c.1713-1720). He was a disciple of the painter Giuseppe Nasini (1657-1736), Franchini and Vicenzo Ferrati, who contributed to his artistic training. He was also influenced by Pietro da Cortona and Bernardo Buontalenti. His first work was the design of the catafalque erected in the Cathedral of Siena on the occasion of the death of Prince Ferdinand of Medici.
After spending some time in Rome, Nicolau Nasoni settled in Malta. On this island, he produced illusionist paintings for the Palace of La Valetta at the time of the Grand-Master Friar António Manuel de Vilhena. According to Robert C. Smith (the greatest scholar of Nasoni), he also worked in the palaces of Verdala and San Anton.
In Malta, he met Friar Roque de Távora e Noronha, brother of Jerónimo de Távora e Noronha Leme Cernache, Dean of the Cathedral of Porto, who may have been responsible for his coming to Porto, in 1725.
In Porto, he married a Napolitan in 1729, and they had a son. After his wife died, he married Antónia Mascarenhas Malafaia in 1730 and they had five children.
In the first phase of his career in Portugal, he dedicated himself to scenic painting, Baroque and leading to Rococo, but then he began to be involved in architecture, quickly becoming a leading figure of art in Porto in the first half of the 18th century.
Between 1725 and 1733 he performed tempera painting for the Cathedral of Porto: in the chancel, sacristy and probably in the church itself. He painted the vaults of the central nave and side naves of the Cathedral of Lamego (around 1737-38). He painted the church of Santa Eulália da Cumieira, in Santa Marta de Penaguião, the church of the Convent of S. António de Ferreirim, in Lamego, the Church of Tarouca, the Casa do Despacho, the church of the Venerable Ordem Terceira de S. Francisco and the Freixo Palace, in Porto.
As an architect, he designed the church, the secretary-infirmary and tower of Clérigos, and designed the plans for the Episcopal Palace of Porto (1734). He designed fountains and springs, for example, the one found in the Sanctuary of Nossa Senhora dos Remédios, in Lamego, and the Anjo S. Miguel, near the entrance of the Cathedral of Porto. He also designed the new façade of the Church of Bom Jesus de Matosinhos (1743-48), his only work of a horizontal nature, rebuilt the Church of Santa Marinha, in the waterfront area of Vila Nova de Gaia (1745), and participated in the construction works of the Church of Misericórdia in Porto between the first and second half of the 18th century. For this church, he designed a majestic Rococo style façade.
Nicolau Nasoni was the author of projects for the Casa do Despacho of the Venerable Ordem Terceira de S. Francisco, in Porto (1746-52) and for the Church of Santiago de Bougado, as well as two plans for the Jail and Court of Appeal of Porto. He designed noble houses in Porto and surroundings, such as the estates of Santa Cruz do Bispo, Bonjóia and Prelada, and Freixo Palace; he also designed sacristy basins, holy water basins, garden decorations, and jewellery.
He died in Porto on 30 August 1773, and is buried in Clérigos Church.