The 22-year-old becomes the latest attacking reinforcement in Patrick Vieira's squad after they completed the permanent signing Kasper Dolberg and Alexis Claude-Maurice this week.
Ounas will be aiming for regular playing time at Nice this season after playing a bit-part role for Napoli during the 2018-19 campaign where he played 18 Serie A matches, including six starts with three goals scored.
📱 Adam, tu as un message... pic.twitter.com/AjSZu5GXUj— OGC Nice (@ogcnice) August 30, 2019
The move marks a homecoming affair for the former Bordeaux player who was born in France. He will unite with compatriot Youcef Atal, Tunisia's Bassem Srarfi and Senegal duo Racine Coly and Ignatius Ganago at the Allianz Riviera.
He scored three goals in three appearances in the continental showpiece.