Giovanni I Participazio (or Particiaco) (died 837) was the tenth (historical) or twelfth (traditional) Doge of Venice from the death of his brother in 829 to his arrest and deposition in 836.

When Giustiniano returned, Agnello was deposed and Giovanni, who was part of the pro-Frankish faction, was exiled to Zara (in today's Croatia).

The first problem was the return of Obelerio degli Antenori, Doge of Venice from 804 to 811, from Constantinople after twenty years of exile.

A revolt in Venice itself placed one of the tribunes, Caroso, on the throne for less than six months, during which Giovanni, surprised by the participation of trusted family members in the rebellion, resided in refuge at the court of Lothair, King of the Lombards.

His dictatorial rule provoked an aristocratic reaction, led by the Mastalici, and one night in 836, an ambush was laid at the exit of the church of S. Pietro in Olivolo.