Sydney commuters no longer need an Opal card to use the city's public transport, which is now fully contactless after the roll-out of the technology to the bus network was completed on Monday.

Instead of an Opal card, bus passengers can now tap on using a credit or debit card, or a smartphone or other device linked to their financial institution's card.

All Sydney transport users can now tap on with a credit or debit card or enabled device, although an Opal card is still required for commuters to access concession discounts. Credit:Michele Mossop

NSW Transport Minister Andrew Constance said the move "marks the final piece of the contactless payments puzzle".

It follows the rollout of the technology to the state's ferries and light rail in March last year, and then to trains in November.