Instead of paying the current 1 euro ($1.33) fee to get into a public bathroom, tourists who think ahead can get one week or day passes to the lavatories online.
Visitors can pay 7 euros online for 10 toilet visits over 5 days in high season, and 5 euros in the low tourist season.
For a regular toilet card, bought at a bathroom or other site, the corresponding costs are 9 euros and 7 euros.
The online day rate for 2 visits is 1 euro in low season, 2 euros in the high season. Otherwise, the card costs 1.50 euros and 3 euros respectively.
"For people who want some security, who don't want to go into a bar to buy a coffee or a roll, so they can go to the bathroom, this is a solution," a Venice city spokesman said.
The online bathroom pass is accessible starting February 1 as part of the city's Venice Connected card which gives access to various services and allows reservations online. The purchase has to be made at least 15 days before use.
City residents pay 25 euro cents per visit to the public bathrooms.
The pass is another attempt by Venice, which hosts about 20 million visitors a year, to deal with tourists who use the streets as urinals.
Tourists, who face "no toilet" signs at many restaurants and cafes, were in favor of the move.
"I'm not used to paying to go to the toilet anyway, but if you haven't got a coin on you, but you need to go to the toilet, you have the card ready to go," said Zoe Dawson, a 20-year old bar waitress from Surrey in England.
Editing by Paul Casciato