It might have been their opening game in Pool C, which also includes Australia, Portugal and Georgia, but the contest against the Fijians was seen as key to Wales's hopes in the tournament in France.
After losing six of eight internationals in 2023, Wales will hope the victory offers some redemption and breathes life into a beleaguered squad.
Victory was almost stolen at the end by the Pacific islanders, who were seeking to rally from an 18-point deficit and could have completed an unlikely comeback but for a knock on with the tryline at their mercy.
Both teams scored four tries in a game full of line breaks, exciting running and bruising clashes that had the crowd on the edge of their seats, especially at the end as Fiji fought back from 32-14 down.
Josh Adams, George North, Louis Rees-Zammit and Elliot Dee crossed for Wales, with Dan Biggar adding two penalties and three conversions.
Fiji's try-scorers were Waisea Nayacalevu, Lekima Tagitagivalu, Josua Tuisova and Mesake Doge.
The Wallabies are next up for Fiji, with the teams due to meet at Saint-Etienne's Stade Geoffroy-Guichard at 1.45am on September 18 (AEST), while Wales take on Portugal the previous day.
