Giovan Battista Cavagna, or Cavagni (died 1613) was an Italian architect, engineer and painter. He was active mostly in Naples.
He was of Roman origin. In Naples he worked in 1572-1577 at the church of San Gregorio Armeno together with Giovanni Vincenzo della Monica. In 1578 he was in Rome, where he is mentioned together with painters Federico Zuccari and Scipione Pulzone at the Academy of St. Luke. Back in Naples, in 1589 he worked to several transition edifices from Renaissance to Mannerist styles, such as the Monte di Pietà, the apse of Sant'Anna dei Lombardi; he also succeeded Francesco Grimaldi in the direction of the construction of San Paolo Maggiore.
In 1601-602 he was also entrusted the construction of the grain stores. He stopped working in Naples in 1605, when he was appointed as architect of the Basilica della Santa Casa of Loreto, in the March. In 1608 he designed the church of San Pietro in Valle at Fano. He died at Loreto in 1613.