Bowyer, a Labour councillor in the London borough of Lambeth, joined Weber Shandwick in November 2000. His clients include DHL International, recruitment agency Monster and Battersea Power Station.
He has also led the agency's public affairs account for Blackpool Challenge Partnership, the public-private body set up to regenerate the Lancashire town and make it the 'Las Vegas of the north'.
Until last year Bowyer led the Nestlé account. Prior to Weber Shandwick, Bowyer spent four years at agency BSMG Worldwide (formerly Charles Barker).
He was a Labour Party press officer during the 1997 general election campaign and worked as a media and policy adviser to then shadow sports and tourism minister Tom Pendry.
Weber Shandwick UK & Ireland chief executive Colin Byrne confirmed that Bowyer, who is officially on a six-month notice period, would join Apex at the end of the year.
Apex declined to comment on Bowyer's hire. Apex is based at the
offices of sister consumer agency Biss Lancaster. It will aim to tap into the client base of the Euro RSCG family of agencies (PRWeek, 7 October).
Owen spent 12 years as Straw's special adviser before quitting after the May general election.