The agreement covers the offshore Cyrenaica basin contract area 44, which was awarded in October during the second round of EPSA IV licensing.
Area 44 comprises 2.5 million acres and is located in water depths ranging from about 10 to more than 10,000 feet.
Both Exxon and Mobil once had significant business interests in Libya, producing the country's first oil field and shipping oil to market.
However, the companies pulled out of Libya in the early 1980s after US-Libyan relations deteriorated.
All Western companies exited Libya in the late 1980s after the US and EU imposed trade sanctions on Colonel Muammar Gaddafi's regime, which they said sponsored terrorism. The embargo was lifted last year.
"We are pleased to be back in business in Libya," said Phil Goss, president of ExxonMobil Libya.
"We look forward to working with (NOC) and the Libyan government to achieve great successes in Libya once again."
