The Kuala Lumpur-headquartered state player has signed a production sharing contract for Block F14.
Speaking at the signing ceremony in Libreville, Petronas vice president for international exploration Effendy Cheng said that the Malaysian explorer would focus on the emerging deep-water pre-salt play with its re-entry to Gabon.
The permit spans around 2500 square kilometres in surface area in water depths of between 2000 and 2500 metres.
Petronas will hold an 80% interest with the government of Gabon retaining 20%.
Earlier this week US independent Marathon Oil gained another deep-water PSC off Gabon at Block G13 (Tchicuate), while Australia's Woodside Petroleum farmed in to Noble Energy's Block F15.