Baldassarre Longoni was an Italian artist who flourished between the 19th and 20th centuries. He was a prominent figure in the Divisionism movement and was known for his portraiture, landscape, and naturalism artwork.

Longoni joined Divisionism after completing his studies at the Brera Academy and was influenced by Vittore Grubicy. His paintings were well-received by critics and he became a member of the Permanent Society in 1898.

Longoni participated in various exhibitions and won the Prince Umberto prize in 1910. He taught painting at the Cignaroli Academy in Verona from 1914 to 1923 and then returned to Como where he continued his artistic career.

Longoni's predominant subject from the 1930s was landscape, and he approached the naturalism of the Lombard tradition.