State parliament passed the legislation in September but the government delayed implementing the measures until Monday because of the COVID-19 pandemic.
Environment Minister David Speirs says the new laws ban the sale, supply and distribution of a range of single-use items.
He says more will be added to the list in early 2022, including polystyrene cups, bowls and plates.
Fines can be issued for any businesses that don't comply but, with strong consumer support for the new laws, the government believes companies will be happy to embrace the change.
"By being a first-mover nationally we've already seen businesses who manufacture re-useable and compostable alternatives start to set up in South Australia," Mr Speirs said.
"Our ban will have significant economic benefits and create local jobs, as well as being good for the environment."