Little is known of his early Church career but he was elevated to cardinal by Pope Urban VIII at the request of Ferdinand III, Holy Roman Emperor in 1641 and this was published in the consistory of 16 December that year. However, the First War of Castro broke out between Barberini Pope Urban and the Farnese Dukes of Parma. As a result, Rinaldo d'Este refused to travel to Rome to receive his cardinal's hat. Instead, when Pope Urban died in 1644, he travelled to Rome to participate in the Papal conclave which elected Pope Innocent X who then conducted the ceremony following his own Papal coronation.