Tilstone replaces Ian Hughes who has left the business and joined a leasing company.
Tilstone has been with Citroen since 2000 and has held a number of roles, latterly as head of digital marketing in a role he took up in 2007.
He has previously held roles in fleet and leasing. Tilstone takes up his new role on 1 November and will report to Linda Jackson, managing director of Citroen UK.
He will oversee a staff count of around 25. Citroen works with Havas agency Euro RSCG in the UK and its media agency is Omnicom-owned OMD.