Annastacia Palaszczuk has become the first woman to lead a state opposition to an election victory in Australia following Labor's victory in the closest Queensland election in 20 years.
She will be sworn in as the state's 39th premier along with her interim ministry on Saturday morning, only three years after the ALP suffered a historic drubbing.
Labor has 44 seats in the 89-seat parliament, with the LNP claiming 42 and Katter's Australia Party winning two.
Sunshine Coast MP Mr Wellington's support gives Labor a one-seat majority in a hung parliament.
Within two hours of the last seat being declared, LNP leader Lawrence Springborg and Ms Palaszczuk visited Governor Paul de Jersey.
But only the Labor leader was smiling when she left, stepping out of her car to give the news to the waiting media pack.
"The governor has invited me to form government. I have accepted that offer," Ms Palaszczuk said.
"It is an extremely humbling experience, and tomorrow the interim ministry will be sworn in here at Government House."
Shortly afterwards, Mr de Jersey tweeted a picture of himself shaking hands with Ms Palaszczuk.
"This afternoon I received @AnnastaciaMP and invited her to form government," he wrote.
Mr Wellington said he was proud to be supporting Ms Palaszczuk.
"We won't agree on everything but I know her heart's in the right place and I certainly believe I've done the right thing for Queensland," he told the ABC.
Mr Springborg congratulated Ms Palaszczuk and Labor, and said the election proved Queensland had a strong, functioning democracy.
"I wish them all the very best in their deliberations over the next few months, and potentially over the next three years as well," he said, alluding to the LNP's potential challenge to the result in the seat of Ferny Grove.
A Palmer United Party candidate was disqualified for being an undisclosed bankrupt, and the opposition could take the result to the Court of Disputed Returns.
If a by-election were held in the next few months and the LNP won the seat, it could form government with the support of Katter party MPs.
But Professor Clive Bean of the Queensland University of Technology said the Katter MPs would play a crucial role anyway.
He said Labor would have to choose a Speaker and if that person came from its own ranks it would mean that, with the support of Mr Wellington, the party would be tied with the LNP and Katter MPs.
"Although the speaker is allowed a casting vote, it is highly unusual and not something that we have generally seen in practice," Prof Bean said.
"It will be interesting to see whether Annastacia Palaszczuk nominates a Labor member, Peter Wellington or even one of the Katter members and then of course whether that nomination is accepted."
Ms Palaszczuk's government faces many other hurdles and the majority of her MPs have no experience in parliament, let alone government.
She has also promised she will cut the number of ministers from 19 to 14.
