Fox, who helped managed the airline's launch in September, will now be responsible for the firm's reputation across Europe on a permanent basis, and will manage Citigate Dewe Rogerson's European account.
She will be based in Lisbon and will target business travellers and wealthy individuals with the Jet Republic's concept of creating a 'private club in the sky'.
Fox was most recently a director at travel specialist Mason Rose, where her work included the repositioning of the Ritz-Carlton hotel company in the UK.
Prior to this she was a director at Halpern specialising in travel and lifestyle. She is also a former MD of agency Talk Luxury.