Italy's Culture Ministry and the Generali insurance company will split the €5 million bill for the restoration, which will improve bridge links to the site as well as funding a cafe and other facilities in the often overlooked green oasis.
The small gardens were built on Napoleon's orders in the early 19th century, and can be found between Saint Mark's Square and the Grand Canal.
The project will restore the "enchanted site" to its "ancient splendour and significance," according to Adele Re Rebaudengo, President of the Venice Gardens Foundation.
She said the gardens would be updated "in a formal and precise way, in keeping with its historic nineteenth-century design, but at the same time filled with the unexpected".
Generali CEO Philippe Donet said Venice was a city "of utmost importance for the company", which has its headquarters in nearby Trieste, and takes its company symbol from the old flag of the Republic of Venice.
The announcement comes less than a week after fashion house Gucci announced it was funding a revamp of Florence's Boboli Gardens. Recent years have seen a string of famous Italian sites renovated with funds from private donors, many of them from the luxury fashion sector.
A multi-million-euro makeover of Rome's Colosseum has been largely funded by fashion and shoewear group Tod's. The amphitheatre was sprayed with water to remove centuries of grime, and the arched facades were strengthened.
Meanwhile, Roman fashion house Fendi paid for a 16-month clean-up of the Trevi fountain which has been acclaimed by visitors. The nearly 300-year-old monument, visited by millions of tourists every year, hit the headlines in 2012 after bits of its elaborate cornice began falling off following a particularly harsh winter.
And the €1.5 million renovation of the capital's Spanish Steps was financed by jeweller Bulgari, which has a store nearby.
The cash-strapped Italian government has also appealed to private businesses to help save other heritage sites, including Pompeii.
Photo: Stew Dean/Flickr