South Sudan has ordered oil companies to restart production immediately.
Production was halted in January in a row with Sudan over oil transit fees. Tensions between the neighbours escalated to the brink of war.
The BBC reports a deal was signed last month and ratified by the Sudanese parliament on Wednesday.
Petroleum minister Stephen Dhieu Dau said it would be three months before oil reached international markets.
South Sudan seceded from Sudan in July 2011, taking two-thirds of the oil, but Khartoum retained the processing and export facilities. Their joint border is also in dispute.
The two economies were seriously damaged as a result of the stoppage - oil accounts for some 98% of South Sudan's revenue.