The first two goals came after corners with captain Serge Aurier poking the Elephants ahead on 67 minutes and Christian Kouame doubling the lead with his head nine minutes later.
Ibrahim Sangare netted a third goal on 89 minutes for the now rampant home team before Leicester City forward Patson Daka claimed a consolation goal in added time. Playing under Croatian coach Aljosa Asanovic for the first time, Zambia fell behind after their best spell of the match as they seek to end a humiliating run of three failed qualification campaigns.
Gasset, 68, who has no previous coaching experience in Africa, succeeded compatriot Patrice Beaumelle, who was dumped after failing to qualify for the 2022 World Cup and making a last-16 exit from the 2021 Cup of Nations.
Although automatic qualifiers as hosts, the Ivorians are playing in the elimination competition to gain match practice.