Tommerup stepped down from the helm of MHI Vestas at the start of April, after four years in the role, handing the reins to Philippe Kavafyan.
He now joins the Fred Olsen Windcarrier subsidiary on the board of directors.
"Jens is a strong wind industry profile and he has a thorough understanding of the market we are operating in," said GWS CEPO Lars Bo Peterson.
"His experience from the OEM perspective and industry as a whole will be very valuable for Global Wind Service and our clients."
GWS claims a track record in over 40 countries, providing advice and O&M to onshore and offshore wind projects.
In May, the firm acquired all offshore and blade activities from installation and service provider Total Wind Group, after it declared bankruptcy.
"I find the history, entrepreneurial spirit and strong knowledge base of Global Wind Service appealing and I am looking forward to working closely with the board and management of GWS," Tommerup said.
As well as MHI Vestas, Tommerup previously led Vestas in the Asia-Pacific region, as well as holding executive roles at coatings specialist Hempel and shipping firm AP Møller-Maersk.
Alongside his new role, he is also expected to join the board of vertical axis floating wind turbine designer SeaTwirl at an extraordinary general meeting in September.