Baroness Delyth Morgan of Drefelin, chief executive of the research charity Breast Cancer Campaign and previously head of Breakthrough Breast Cancer, which campaigns for earlier diagnosis, will become chief executive of the new charity formed from the merger of the two next month.
The two charities, which together have 212 staff and a combined income of £28.3m according to their most recent annual accounts, announced in November that they would merge.
The new charity will officially be created on 1 April and will move to a new office in Aldgate in London.
Morgan has been a crossbench member of the House of Lords since 2004, although she previously sat for the Labour Party. She has been the chief executive of BCC since July 2011 and was the chief executive of Breakthrough between 1995 and 2005.
She was appointed by the new charity’s board of trustees on 13 March after an open recruitment process.
A spokeswoman for Breast Cancer Campaign was not immediately able to confirm what Morgan’s salary would be.
A spokeswoman for Breakthrough said that Chris Askew, chief executive of the charity, would be leaving, but was unable to say when he would leave or what he would be doing next.
Morgan said: "This job to me is both professional and personal. It is a great honour and leadership challenge to have been selected to lead these two great charities, merging into one to finally end breast cancer.
"Leading this new charity is the opportunity to finish the job. Collaboration and enterprise will be essential – we must harness the incredible progress in science to deliver more targeted treatment, using a strong single voice to aid consistently high-quality care, early detection and prevention wherever possible."