Girolamo Rainaldi (1570 - 1655, Rome) was an Italian architect in the Mannerist style.

Rainaldi was responsible for brining the Mannerist style to prominence in Rome. He became the chief architect of Rome in 1602 and for the papacy in 1644. His important projects in Rome and its environs include San Silvestro, located in Caprarola and the Pamphili Palace (c. 1650). Rainaldi was brought to Parma by the Farnese family to build their town palaces amd also did the vaulting of Santissima Annunziata. He was also active in Bologna, where he built the Church of Santa Lucia (1623), and Modena, where he contributed to the construction of the Ducal Palace (1631-34). His son, Carlo Rainaldi, was also a notable architect.