The French side scored eight tries through Jean-Baptiste Gros, Sipili Falatea, Aaron Grandidier Nkanang, Kalvin Gourgues, Theo Attissogbe, Charles Ollivon, Antoine Dupont and a penalty try. Gourgues and Maxime Lucu added 12 points with the boot.
Vinaya Habosi and Selestino Ravutaumada scored Fiji’s two tries, both converted by Ben Volavola.
France are on 17 points, two clear of Ireland, but lost flyhalf Romain Ntamack to injury during the first half.
Fiji are bottom of the Southern Hemisphere section without a point before heading to Ireland next week.
Despite missing a string of players, including flyhalf Matthieu Jalibert and fullback Thomas Ramos, France managed to secure a third win in four matches in the new competition.
"We are very happy with the result," Attissogbe told TF1.
"We knew it was important to take the win, given the results of the other nations. We are carrying on with our momentum."
The match started shakily for France with a series of early errors, but Gros settled their nerves by powering over in the 15th minute. The forwards dominated the first half, with a penalty try awarded after a driving maul led to Isoa Nasilasila's yellow card.
Eleven minutes later, tighthead prop Falatea ended a long attacking move, seconds after Ntamack injured his shoulder.
Winger Grandidier Nkanang claimed the bonus point just before halftime, capitalising on an interception mistake by Vilimoni Botitu to send France into the break with a commanding 26-3 lead. Fiji's only first-half points came from a Simione Kuruvoli penalty.
The second half continued in the same vein, though France endured a scrappy 20-minute spell before Gourgues and Attissogbe, finishing off a slick counter-attack started by Antoine Dupont and continued by Louis Bielle-Biarrey, added tries in quick succession.
Attack dominated the last quarter, with two tries for each side. Fiji responded with a solo effort from Habosi, who beat four defenders to cross the line and Ravutaumada finished under the posts.
Charles Ollivon powered over and Dupont crossed for France’s seventh and eighth tries.
French celebrations were dampened by Ntamack’s injury ahead of their next game against world champions South Africa.
"Romain (Ntamack) came off after that injury and we won’t have him for the rest of the competition," France coach Fabien Galthie told TF1.
"An examination revealed a fairly serious shoulder injury."