A plenary session of the European parliament accepted a recommendation from its legal affairs committee not to lift Philippot's immunity from prosecution on the grounds that MEPs cannot be detained or prosecuted for opinions or votes exercised as part of their work as elected representatives.
Philippot immediately hit out at the French government, which had passed on a court's request for his privileges to be suspended, and at Christiane Taubira, who was justice minister at the time the request was made.
"This vote highlights the dishonourable behaviour of the French government and particularly that of the former justice minister, Madame Taubira, who signed in her own hand the request for suspension of privilege, in defiance of the law, following the unprecedented suit by the state of Qatar against myself," he said in a statement.
He called for an inquiry into "possible close - too close - financial links" between Qatar's government and leading French politicians and institutions.
A court in Versailles, near Paris, asked for his immunity to be lifted in September, in response to a libel case filed by Qatar in April.
In the aftermath of the January 2015 Charlie Hebdo attacks, Philippot accused Qatar and other Gulf states of financing jihadi organisations, including the Islamic State (IS) armed group.
To read our reports of the Charlie Hebdo attacks and their aftermath, click here.
On hearing of the case, he stood by his statement, attacking "the dubious links between this radical Islamic dictatorship, as well as the incestuous relationship ... between the country and part of the French political class".
He cited a 2014 European parliament resolution that declared that IS received finance from donors in Qatar, Kuwait and the United Arab Emirates.
To read our reports of the November 2015 Paris attacks and their aftermath, click here.