A ten percent statewide swing has left Labor with up to 30 seats in the 47-seat South Australian parliament.
Premier Mike Rann, who had relied on the support of independents for his previous minority government, pledged to "continue to get results for South Australia" during his second term.
In Tasmania, Labor has won 14 seats, giving it the power to govern in its own right, despite a two per cent swing against the party.
Labor Premier Paul Lennon promised continued economic growth and to lead Australia's reconciliation efforts after Labor won a third successive term.
He pledged to resolve "once and for all" the issue over the stolen generation.
"Until we make our final peace with our Aboriginal people we won't be the culturally confident society that I want Tasmania to be," he said.