His two earliest known works date back to this period: two statues of saints, made of chalk, in the Oratory of Santa Maria della Vita in Bologna.

By the age of twenty, Ferdinando I, Duke of Mantua, began commissioning works from him, and he was also employed by local jewelers for figurative designs.

[2] After a short residence in Venice, he went to Rome in 1625 with an introduction from the Duke of Mantua to the late pope's nephew, Cardinal Ludovico Ludovisi, who employed him for a time in the restoration of ancient statues.

[3][a] Propelled by the Borghese and Barberini patronage, Gian Lorenzo Bernini and his studio garnered most of the major Roman sculptural commissions.

The arrangement mirrors the one designed by Bernini for the Tomb of Urban VIII (1628–47), with a central hieratic sculpture of the pope seated in full regalia and offering a hand of blessing, while at his feet, two allegorical female figures flank his sarcophagus.

[5] In 1635–38, Pietro Boncompagni commissioned from Algardi a colossal statue of Philip Neri with kneeling angels for Santa Maria in Vallicella, completed in 1640.

These works established his reputation, alongside two reliefs of The Martyrdom of St Paul and The Rest on the Flight into Egypt (a contemporary replica of the latter is now in the Victoria and Albert Museum).

In the villa grounds, Algardi and his studio executed sculpture-encrusted fountains and other garden features, where some of his free-standing sculpture and bas-reliefs remain.

The subject was apt for a papal state seeking to increase its power, since it depicts the historical legend wherein Saint Leo the Great, the first pope to receive the epithet, with supernatural aid, deterred the Huns from looting Rome.

Algardi's patron's message through the relief would be that all viewers should be sternly reminded of the papal capacity to invoke divine retribution against enemies.

Algardi's classicizing manner was carried on by pupils, including Ercole Ferrata and Domenico Guidi, and Antonio Raggi initially trained with him.