Initial results released at around 8.25 pm on Sunday night suggested Fillon had easily beaten his rival Alain Juppé.
Fillon, a conservative former prime minister, had 68.7 percent of the vote to 31.3 percent for his centrist rival Alain Juppe, results from 3,565 out of 10,229 polling stations showed.
The votes will be updated throughout the night, but with such a large lead, Fillon appears home and dry.
TV images showed his supporters celebrating and singing the Marseillaise. Alain Juppé is expected to concede defeat at some point in the evening.
Between 4.2 and 4.6 million French voters cast ballots on Sunday to pick the presidential candidate for the centre-right Republicans party.
The US-style primary contest, the first for the party, was a battle between socially conservative and economic “radical” Fillon and the more moderate Alain Juppe, also a former prime minister who is nine years older at 71.
The French presidential vote is seen as a key test for mainstream political parties after the success of Donald Trump in the United States and the Brexit campaign in Britain, both of which harnessed anti-elite, anti-establishment anger.
Polls opened at 8:00 am (0700 GMT), with all French voters who pay two euros ($2.10) and state they share the values of the centre-right allowed to cast a ballot.
Fillon will now face fierce competition from far-right National Front leader Marine Le Pen, who is waiting in the wings ready to attack the victor as a symbol of France’s ruling class.
Fillon, a career politician and prime minister from 2007-12, has warnedthat France is “on the verge of revolt” and believes his plan to slash 500,000 public sector jobs and business regulations is the tonic the demoralised country needs.
“I’ll do everything for entrepreneurs!” he declared at his final rally on Friday night in Paris, promising to help businesses create the jobs needed to lower France’s stubbornly high unemployment rate of around 10 percent.
The devout Catholic and motor racing fan has also won support with his hard line on Muslim immigrants, as well as an emphasis on protecting France’s identity, language and family values.
He demanded Friday that “the Islamic religion accept what all the others have accepted in the past… that radicalism and provocation have no place here.”
Article source: http://www.thelocal.fr/20161127/fillon-set-win-rightwing-primary-runoff-initial-results-show