Backwell is a former journalist and analyst who has covered energy markets in Europe, the US and Latin America and most recently served as the managing director of FTI Consulting's clean energy unit.
Sawyer, who joined GWEC as its first secretary general in 2007, will continue to act as the council’s senior policy advisor.
Between 2007 and the end of 2017, global wind installations grew from 74GW to 539GW.
GWEC chairman Morten Dyrholm said: "We are extremely grateful to Steve Sawyer, who has played a big part in the success of GWEC and the global wind sector over the past 11 years.
"We are pleased that we will continue to be able to count on Steve’s knowledge and network in his new role as senior policy advisor."
During his career Backwell has advised many of the leading technology companies, utilities, developers, independent power producers and financial institutions active in the wind power sector.
"The wind industry has seen phenomenal growth over the last ten years, and is well-placed to cement its position as one of the world’s leading energy sources, providing clean, cost-effective power for the digital age," he said.
"However, the wind sector will need to negotiate a series of market, regulatory, political and technological challenges over the coming period.
"Within this context, GWEC will need to play a central role in helping the sector and the organisation’s members to achieve their objectives."