Bernard Mounier joined the Bouygues group in 1983 as a works supervisor.

After holding various operational and executive positions within Bouygues Construction in the Paris region, he was appointed Chairman of Bouygues Bâtiment Ile-de-France in 2015.

On 1 September 2018 he was appointed Deputy CEO of Bouygues Construction with responsibility for Bouygues Bâtiment France-Europe and Purchasing policy. He was also a member of the Bouygues Construction Executive Committee.

On 19 February 2021, he was appointed Chairman of Bouygues Immobilier. He is also Chairman and director of the Bouygues Immobilier Corporate Foundation.