World No. 11 Nishikori needed one hour and 28 minutes to win his first career encounter with Mannarino, World No. 46, reports Efe.
The 10th-seeded Japanese player will next take on either seventh-seeded Kevin Anderson of South Africa or Nikoloz Basilashvili of Georgia, World No. 22.
How far Nishikori advances in Paris will determine whether he secures a place in the ATP Finals, which kick off on November 11 in London, as he needs to reach at least the semi-final round.
(With inputs from agencies.)