Boussagol (pictured) retains her previous role leading the Belgian business of APCO.
She replaces Nicolas Bouvier, who was also MD for France. A six-year veteran of the firm, Bouvier became a partner at Brunswick in Paris in December.
APCO has also taken on Nicolas Castex to succeed Bouvier as France MD, overseeing the Lyon and Paris offices. Castex founded Citigate Dewe Rogerson's Paris office in 2004 and had served as managing director ever since.
A long-time APCO servant, Boussagol has led the Brussels operation for three-and-a-half years, prior to which she was MD for France.
Global CEO Brad Staples said: "Claire’s record for nurturing enduring pan-European and global client relationships throughout her 21-year career with APCO provides a strong foundation for future success in this new role."