Born at Sora, son of Giacomo Boncompagni, 1st Duke of Sora, Aquino, Arce and Arpino, 1st Marquess of Vignola, and wife Costanza Sforza di Santa Fiore.
He was a nephew of Cardinals by both maternal and paternal sides: Filippo Boncompagni (1572) and Francesco Sforza (1583).
Filippo studied at the University of Bologna, where he earned a doctorate in utroque iure, both canon and civil law, on May 20, 1615.
He moved to Rome and was named referendary of the Tribunals of the Apostolic Signature of Justice and of Grace in 1615.
He was created cardinal deacon in the consistory of April 19, 1621; received a dispensation for having an uncle in the Sacred College of Cardinals He participated in the conclave of 1623, which elected Pope Urban VIII.