Born in Viterbo to Laura de Angelis and Bartolomeo Romanelli, he went to Rome at age 14 to study to become an artist, and within a few years became part of the household of Cardinal Francesco Barberini. He was a pupil in the painting studio of Pietro da Cortona, the leading painter of his day, but the two eventually quarreled and so Romanelli left.
Romanelli was born in Viterbo to Laura de Angelis and Bartolomeo Romanelli, and at 14 he moved to Rome to study art. He became part of Cardinal Francesco Barberini's household and studied under Pietro da Cortona, but their disagreement led to Romanelli's departure.