Bowen, who also led his own consultancy, Sam Bowen Publicity, has more than 20 years of experience as a comms expert.
Kwittken's European office was established in 2010 and has approximately 20 staff.
Bowen said: "This is a terrific opportunity to work with a diverse roster of high calibre clients and dynamic communications professionals and I am looking forward to contributing to the growth of our European business."
The agency’s co-founder, Aaron Kwittken, will move into the position of global chairman and CEO.
He said: "I’m exceptionally proud of our organic and new business growth and the work we’ve done this past year that has enabled us to hire great talent like Sam.
"We look forward to further accelerating our agency’s growth and imprinting our work across additional regions outside the United States, in the near future."