According to The National's reporter Malum Nalu, Somare and his cabinet were sworn in at government house by Ogio.
Somare will reportedly be driven to Morauta Haus - home to key government offices in Waigani - where a press conference is expected to be held later today.
Events of yesterday afternoon
As of yesterday, Ogio reportedly could not "understand" the recent Supreme Court judgement which called for Sir Michael Somare to be immediately restored as prime minister.
The court judgement stated Peter O'Neill was not lawfully appointed as prime minister on August 2, the fateful day on which he won an overwhelming parliament vote to be elected as the new national leader while Somare remained in Singapore on extended medical leave.
O'Neill and about 60 of his colleagues pushed through police at government house yesterday afternoon to speak to Ogio.
They shouted "we're unarmed and we're the legitimate government" at the time, according to the ABC.
While Sir Michael Somare did not show up as expected to be sworn in, a secretary reportedly told O'Neill and his colleagues Ogio was confused "by the court order and essentially could not understand it".
According to the report, the secretary said Ogio wanted O'Neill and Somare "to get together and sort out the disagreement themselves".
Though the court has ruled Somare is the rightful prime minister, the O'Neill coalition has a vast majority in parliament and has taken unprecedented moves to introduce retroactive amendments aimed at securing O'Neill's position as PM.
Retrospective laws are typically not appreciated by common law courts, providing ample opportunities for a legal challenge.
The Supreme Court orders were clear and the fact Ogio did not want to follow them yesterday was a worrying outcome in itself.
The situation facing the governor general in PNG has been compared to the fiasco that marked the end of the Whitlam government in Australia - which resulted in an early election.
To view the three scans of the relevant part of the court orders please click on the image links to the right of the screen under related links and downloads.
More complications are expected today.
At around 9.40am in Port Moresby, ABC correspondent Liam Fox tweeted he was told Somare's ministers had been sworn in at government house - indicating Ogio decided in favour of the Somare camp.
He also reported the O'Neill coalition passed a motion for Ogio to attend parliament to swear in O'Neill as prime minister.
There were earlier rumours "O'Neill and co" were preparing to sack Ogio but Fox later said there was no such move on the cards.
The O'Neill coalition might not accept any decision to install Somare as PM, going by its resistance to date.