This church and an adjacent monastery were founded in 1620 by the Franciscan order of the Riformati (which gave the name to the Fondamenta dei Riformati in front). These Franciscans friars relocated from the island monastery of San Francesco del Deserto and received funding from the wealthy Zen family to build this religious complex on reclaimed land in northern Cannaregio, not far from the church of Sant’ Alvise.
The church is dedicated to St. Bonaventure (1221-1274), an Italian theologian and early follower of St. Francis of Assisi.
After the fall of the Venetian Republic and the great suppression of churches, the church and monastery were closed. The place was used as a factory and for other secular purposes until 1859, when it was purchased by a Venetian countess who gave the complex to the Carmelite nuns of Santa Teresa. In the early 20th century, the nuns ran a children’s hospital here, and the church was the private chapel for the convent.
The nuns are still there today and Mass is celebrated daily at 6:30 in the morning according to the Patriarch of Venice website. I've never found it open and going to Mass might be the only way to visit it. The church was behind scaffolding a few years ago – not sure if the restoration is completed yet or not.
This Google Earth view shows the cloisters, gardens, and so many trees.