Gilles Ballerat holds a postgraduate diploma (DESS) in mathematical decision engineering from the University of Lyon I. He began his career in 1991 when he joined the SNCF. After holding a number of operational and functional management positions, in 2000 he became Chief of Staff to the Deputy Director General of Customer Services, before taking over the management of the Corsican Railways subsidiary in 2003.

Between 2009 and 2013, he was Territorial Director of SNCF Gares & Connexions for the South of France. He oversaw the modernization of the region's stations with local authorities.

From 2014 to 2019, Gilles was Director of Services and Operations for SNCF Gares & Connexions, responsible specifically for customer service, station operations (passenger information systems, maintenance, etc.) and station management. He managed 2,500 employees.

In 2019, Gilles joined the Group's property department (which has 8 million square meters of buildings) as Director of Property Strategy and the Work Environment. His remit consists in defining and implementing projects and strategies for transforming, optimizing and operating the real estate used by SNCF.

At the same time, he was Managing Director of the property company S2FIT (Société foncière ferroviaire pour l'immobilier tertiaire), which aims to develop the SNCF's property portfolio.