World Rugby chief executive Brett Gosper will step down in January to take up a new role as head of the NFL in the UK and Europe.
Gosper joined World Rugby in July 2012 and oversaw the sport's return to the Olympic Games in Rio in 2016 and the delivery of the first Asian World Cup in Japan last year.
Chief operating officer Alan Gilpin will perform the role of interim CEO until Gosper's replacement is appointed.
"It's been a fantastic nine years," Gosper said. "It has been an absolute privilege to have worked with so many talented and dedicated rugby people around the world.
"Rugby is a wonderful sport and World Rugby is a fantastic organisation, and therefore it was a very difficult decision to leave.
"But with a new ambitious strategic plan set to launch and the strong foundations in place to drive the sport forward beyond the pandemic, the time is right for me to begin a new challenge.
"I am proud of what we have achieved together as a rugby family. While I will miss working in the sport, my passion and enthusiasm for what rugby and its values mean to so many will never diminish."
NFL executive vice president Christopher Halpin added: "The UK has been a core market of investment and growth for the NFL over the last decade, and we believe broader Europe presents a number of similar attractive opportunities to expand the game and our fan base.
"Brett's exceptional skills and experience make him the ideal leader to build on our momentum and grow the NFL."