Barker has spent nine years heading marketing and comms at the British Heart Foundation.
He has now joined Breakthrough Breast Cancer on a one-year maternity cover contract, standing in for Fiona Hazell who departed at the end of last year. Barker will be responsible for a team of 18.
Barker said: 'I want to help build increased awareness and understanding of the vibrant new brand, while ensuring that we effectively integrate marketing and communications efforts across the charity.'
Prior to the BHF, Barker was head of media relations at The Royal National Institute for Deaf People. He has also worked in the private sector.
Breakthrough Breast Cancer is dedicated to the prevention, treatment and ultimate eradication of breast cancer, fighting on three fronts: research, campaigning and education.