The ban was legislated by the South Australian parliament in September last year.
People found to be breaching the laws banning the sale, supply and distribution of single-use items face fines ranging from $315 to $20,000.
The ban comes as Victoria announced it will phase out single-use plastics by 2023.
Queensland has also introduced legislation to ban straws, plastic cutlery and plates from July 2021.
It is a movement that has gained traction around the world.
China, the world's biggest importer of plastic, has banned single-use bags and straws.
The European Union, with nearly half a billion people, has also banned single-use plastic cutlery, plates, cotton buds and polystyrene containers.
Shane Cucow, plastic pollution campaign manager for the Australian Marine Conservation Society, says the action matches the urgency of the situation in our oceans.
Plastic pollution is quickly becoming one of the greatest threats to wildlife in our oceans. Just the last two weeks we saw incidents of baby turtles washing up on North Queensland beaches with plastic in their stomachs, reef sharks with plastic wrapped around their neck and dorsal fin. We've seen whales washing up on beaches with stomachs full of plastic for years now. We can't keep ignoring this problem. What plastic does to our wildlife is it entangles them, or they can eat it. It can cause life-threatening blockages in their stomach or it can cause internal injuries when it's those sorts of sharp plastics like pieces of cutlery etcetera.
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