The defending tournament champions opened the scoring in the fifth minute when a quick pass behind from Aminasi Tuiamba 20 metres from the try line set up an opportunity for Vilimoni Botitu to weave around Remi Siega.
Tuiamba followed with a try of his own for Fiji to lead 14-0 at the break before a yellow card for Josua Vakurunabili saw them concede a penalty.
But the 10th-ranked French could not press the advantage and found themselves back on the defensive even before a high tackle send-off for Tavite Veredamu levelled the playing field.
Tuiamba was sent off with 90 seconds to spare, two minutes after his second try, in a match where the Fijians made full use of their strength advantage.
Fiji’s reliable band of supporters, celebrating the country’s 19th overall win in Hong Kong, cheered and sang in the north stand long after their team had left the championship podium.
The side came into the final after spoiling the United States’ hopes of a maiden Hong Kong Sevens championship with a 28-19 semis win over the series leaders, recovering their customary precision after a scrappy quarter-finals win over Argentina.
The US beat Samoa to third place without injured captain Madison Hughes. They will stay number one on the standings following their Vegas win and four other finals appearances, with Fiji to leapfrog New Zealand into second.
France, continuing the form that saw them runners-up in Vancouver last month, knocked out Samoa to book their first ever finals appearance in Hong Kong after earlier dashing the All Blacks’ chances in a shock 14-12 quarter-final win.
New Zealand lost to Argentina 21-14 in the fifth-place plate final when Kurt Baker was sent off in the 13th minute, giving Matias Osadczuk a crucial opening after the final horn.
Japan meanwhile earned a temporary reprieve from their relegation threat with a 10th place finish, losing 26-24 to Scotland in the bowl final.
– Ireland qualifies –
Ireland will join the world tour next year after a 28-7 win over Hong Kong — a second disappointment for the hometown side after their 2016 qualifying finals loss.
Fans cheered and waved the city’s red and white bauhinia flag from all corners of the stadium but the much-improved squad’s golden run through the tournament ended when Jordan Conroy bagged the winners’ third try in the first minute after the break.
Tom McQueen made the home team’s solitary try soon after Gregory O’Shea was sin-binned for rough conduct in the second half.
“It’s been a long and hard road. I think that we all just stood on the pitch there and couldn’t move,” said Ireland captain Billy Dardis after the win.
“We’re just speechless… It won’t sink in for a couple of weeks.”