In 1981, after the defeat of the conservatives in legislative elections, finding the RPR too moderate, and realizing that not being a graduate from the École Nationale d'Administration like Jacques Toubon or Jean-François Mancel or Alain Juppé was slowing down his political career in the Rassemblement pour la République, he went on to create the Comités d'Action Républicaine (CAR).

A rival of Jean-Pierre Stirbois, then general secretary of the FN (who died in 1988), he organised Le Pen's election campaign in 1987 and became the number two (délégué général) in the movement.

[2] His friends of the Club de l'Horloge Jean-Yves Le Gallou, Jean-Claude Bardet, Yvan Blot and Jean-Jacques Mourreau of the CAR also secured key positions in the hierarchy of the Front National.

Moreover, Mégret started to become very popular with the party members, winning large support against his rival Bruno Gollnisch, who had been made vice-president and general secretary of the Front National by Le Pen in 1995.

[3] Following the social unrest of November–December 1995, Mégret developed a strategy of creating new unions (FN-RATP, FN-TCL, FN-Poste, Mouvement pour une Education Nationale, FN-Police) and professional organisations tied to the Front National to increase the audience of the party.

After he was sentenced to 8 months of probation, 8000 Euro fine and one-year ban from standing in any election for defalcation of public funds, he resigned in 2008 from the political field.

He criticised the leadership of Marine Le Pen for what Mégret perceives to be the "de-demonization and then standardization" of the Rassemblement National, judging her to have 'eroded' the party's firm stance on issues relating to security and identity.