Rainaldi was one of the leading architects of seventeenth-century Rome, known for a certain grandeur in his designs. He worked at first with his father, Girolamo Rainaldi, who brought the Mannerist style to Rome. After his father's death, he fully embraced the monumental Baroque style. His works include the facade of San Andrea della Valle (1661_65), the twin churches of Santa Maria dei Miracoli and Santa Maria in Monte Santo, and Santa Maria Campitelli (1663-67), considered his finest work.
The son of a painter from Norcia, Rainaldi was born in Rome.
Rainaldi, who had adapted for the Farnese two monumental antique granite basins as matching fountains in Piazza Farnese in 1626, was taken to Parma by the Farnese to build their town palaces there, and also did the vaulting of Santissima Annunziata in that city.
Rainaldi was also active in Bologna, where he designed the vaulting to cover the vast and ambitious church of San Petronio (finished on-site by Francesco Martini), and designed the Church of Santa Lucia (1623).