Talks between Salva Kiir (l) and President al-Bashir were crucial
Sudan's power-sharing government is to shift every three months from Khartoum to the southern town of Juba as part of the peace process, officials say.
The move is part of an agreement to improve relations between the predominantly Muslim north and the Christian and Animist south.
The ex-rebel Sudan People's Liberation Movement is to rejoin the government two months after pulling out.
More time has also been allocated to resolve outstanding issues.
A key sticking-point was the demarcation of the disputed oil-rich Abyei region.
The SPLM secretary general, Pagan Amum, said in Khartoum he was hopeful the peace agreement was back on track, and that the dispute over Abyei would be resolved soon.
All outstanding issues had been resolved apart from Abyei, he said.
"We are hopeful that by Saturday there may be a solution - we are hopeful," he added.
The BBC's correspondent in Khartoum, Amber Henshaw, says many people feared Sudan was on the verge of sliding back into the brutal 20-year civil war that ended in 2005 and cost the lives of 1.5 million people.
But the SPLM agreed to end its boycott after its leader Salva Kiir met Sudanese President Omar al-Bashir.
They agreed the three-month rotation as well as funding for a census and a timetable to pull out troops either side of Sudan's north-south border.
One official added the move to Juba would be a symbolic gesture at first "as the facilities [there] are still run down".
Mr Amum said that SPLM ministers would be instructed to return to government.
The unity government will also set up a development commission to speed up road links between the more developed north and the south, which has little infrastructure after the long war.
Under the peace deal, the SPLM leader is also national vice-president.
There are currently 10,000 UN peacekeepers in South Sudan.