Currently global president of Discovery's Animal Planet brand, Dinnage will start at the Premier League early in the new year.
She joined Discovery in 2009 and previously ran its British and Irish operation, which included responsibility for Eurosport.
Dinnage's appointment will come as a surprise to many as she was not mentioned among the early runners and riders, who included former Prime Minister Tony Blair at one stage and more plausibly BBC Studios boss Tim Davie and ITV director of strategy Tom Betts.
But experience of the broadcasting landscape is the key consideration for this job and Dinnage has that in spades, having started her career at MTV and then progressed to Channel Five.
During her time at Discovery, Eurosport was linked with a bid for Premier League broadcast rights and it snapped up the European rights for the Olympics between 2018 and 2024.
According to Discovery, Dinnage has been responsible for "accelerating the growth of Animal Planet across all screens through an ambitious content strategy and clear brand purpose".
She is also a board member of All4media, chair of the Commercial Broadcasters Association as well as being an executive member of the Discovery Women’s Network.
The appointment of Dinnage highlights the league's focus on broadcasting as most of its revenue comes from selling television rights.
Scudamore has overseen the value of those rights soaring 12-fold to more than £8billion.
Chelsea chairman Bruce Buck, Burnley chairman Mike Garlick and Leicester chief executive Susan Whelan led the recruitment process to find the new chief executive and they will now begin looking for a non-executive chairman, as the roles are being split again.
In a statement, Dinnage said: "I am excited at the prospect of taking on this fantastic role. The Premier League means so much to so many people.
"It represents the pinnacle of professional sport and the opportunity to lead such a dynamic and inspirational organisation is a great privilege.
"With the support of clubs and the team, I look forward to extending the success of the League for many years to come."
Additional reporting by the Press Association and Reuters.