He will also handle acquisition strategy across the EMEA region.
The power shift results from discussions involving B-M's global executive board and parent WPP. It comes just a month into the reign of New York-based global CEO Mark Penn.
Heggenes, a Norwegian, had held the role of joint CEO for Europe for almost two years, but said of his new post: 'I want to do it – affiliates are a very important part of the agency's global footprint. And expansion is important to us, too.'
He now finds himself reporting to both Sinclair and Penn: to the former in his continued role as UK CEO and to Penn in his international capacity.
Sinclair, who has been based in Madrid for around a year and now oversees 18 wholly owned offices across Europe, said: 'Per has done a remarkable job turning B-M around in the UK. The task now is to propel it to the next level.'
She added: 'These changes will simplify our structure for clients focused on pan-European campaigns.'
In the US, Pat Ford, chair of the agency's global corporate and financial practice and New York market leader, has been promoted to US CEO. He succeeds Ken Rietz, who is retiring after 15 years with the agency.
Penn replaced outgoing CEO Tom Nides, who joined Morgan Stanley as chief administrative officer.