Sydney is the first city in Australia to use this technology, even though its commonplace in cities like London.
The contactless payment option has been rolled out to light rail and all ferries from today, with New South Wales Transport Minister Andrew Constance announcing he wants it on the train network by the end of the year.
Sydneysiders hopping on and off the city's busy commuter ferries and light rail services can now pass through the turnstiles with a tap of their payment cards and smartphones.
However, they will not get the discounts and caps that come with the Opal card.
Transport Minister Andrew Constance stated that the new system was all about providing commuters with choice and convenience, and stressed that it was not created to replace the Opal altogether but rather to supplement it, much like the Oyster system in London which the Opal is based on.
"It's great news for customer choice and convenience, and it's certainly a model of delivery which complements what is a wonderful foundation when it comes to Opal". He said it is targeted at people looking for convenience.
The trial had originally involved Mastercard customers only.
Open payment will not replace Opal, which is now used by almost 14 million people a week but will provide freedom of choice when it comes to paying for travel.
American Express welcomed the change, and pointed out that both Sydney residents and visitors to the city would benefit from the flexible payment options.
By Amex's count, nearly 60% of Australians use contactless payments and one in six use mobile wallets, which means the option to use these payment methods on their daily commute will likely be a popular one.
"This is the ideal solution if you're a regular commuter who has left their Opal card at home".
If you're travelling with more than one person, you can't all tap on with the same piece of plastic - it's one tap on per card. Across London, more than 2.1 million journeys are now made using contactless on its bus, Tube and rail services every day.