The fourth-term Labor Government in South Australia has four new faces in the ministry.

The team has headed to Government House in Adelaide to be sworn in after Labor formed a minority government with backing from a Port Pirie independent.

Caucus started the day with a meeting at Parliament House, where Premier Jay Weatherill told his colleagues he ALP won the election because it wanted the victory more than the Liberals did.

He says Labor fought from a long way behind to secure its win.

Mr Weatherill thanked all his party MPs for what he described as hand-to-hand war in the trenches to secure each seat.

"Frankly, you wanted to win more than they did because you knew you had a purpose and I stood up next to the Leader of the Opposition in the last debate and I can tell you, by the end of the debate, he didn't know whether he wanted to be the premier of South Australia and that is why we are standing here because we know what we want to do with this state," he said.

Two ministers lost their seats at this month's election, Grace Portolesi and Chloe Fox.

Mr Weatherill is elevating northern suburbs MPs Zoe Bettison and Susan Close to the new frontbench line-up.

Former deputy premier Kevin Foley's ex-chief-of-staff and just-elected MP Stephen Mullighan is getting a portfolio.

Mr Mullighan is the first Labor member since Mr Weatherill to go into the ministry in his first parliamentary term.

The newly elected member for Lee says he feels privileged.

"We've been given a very significant opportunity by the Caucus. It's a significant responsibility that we take very seriously and we're looking forward to working hard for the benefit of South Australia," he said.

Ms Bettison, the member for the northern Adelaide seat of Ramsay, says achieving a ministry has been her political ambition.

"I've always been keen to put my hand forward, obviously to be elevated to ministry is what most people want when they come into politics," she said.

Independent Geoff Brock, who threw his support behind Labor to let it form government, will get the portfolios covering regional development and local government.

Labor will have 24 seats in the new House of Assembly due to Mr Brock's support, the Liberals will have 22 and the other is held by the independent on sick leave, Bob Such.