Girolamo Gianni was a native of Naples. He discovered Malta when he travelled there in 1867, and he eventually settled there with his family for 20 years. He became well-known for small souvenir paintings, but also received many commissions for works in larger format. It seems he should not be confused with Giacinto Gianni.
He specialised in busy Neapolitan street scenes and views of the Bay that included Vesuvius, and similar scenes in Malta, especially Valletta and its port. His paintings are valued for what they show of the life of his times, and he had several followers.