He was adopted by his uncle who, when became pope with the name Paul V, made him Cardinal at age 29. His uncle's favour allowed Borgese to accumulate an immense fortune, which he used to acquire which he used to acquire the vast land-holdings where he built Villa Borghese, now one of the most important Museums in Rome.

Scipione was oriented towards his own sex, and this led to full-blown scandals. In 1605, soon after being made a cardinal, Borghese wanted to bring to Rome Stefano Pignattelli, his intimate "friend".

Paul V compelled Stefano to move out of Shipone's house, but the cardinal doubled his love for his friend and succumbed to a severe melancholy which resuletd in a long and serious illness. Only when Stefano was allowed to return to Rome to look after Scipione, did the cardinal recover.

Shipione's uncle the pope, thereupon decided that in order to keep a check on Pignattelli he must co-opt, rather than combat, him. He had Stefano ordained, the beginning of a carreer which led to his becoming a cardinal in 1621. But Stefano died in 1623. Scipione died ten years later.