Giovanni Battista Mainero (c. 1600–1657) was an Italian painter of the Baroque period, active mainly in his natal city of Genoa. He was the pupil of the painter Luciano Borzone. He died during the plague of 1657.

References

• Soprani, Raffaello (1769). Carlo Giuseppe Ratti (ed.). Delle vite de' pittori, scultori, ed architetti genovesi; Tomo secundo scritto da Carlo Giuseppe Ratti. Genoa: Stamperia Casamara. pp. 255–256. Genovesi Raffaello Soprani.