He will replace Alan Parker who spent six years at the head of the group, which counts Premier Inn, Beefeater and Costa Coffee among its businesses, and 18 years at the firm in total.
Harrison beat other potential candidates including Carl Leaver, former international director of Marks & Spencer, and Patrick Dempsey and Chris Rogers, two strong internal candidates.
Whitbread chairman Anthony Habgood said the five years Harrison has spent running easyJet meant he was an obvious choice for the budget value-for-money brand.
“He ran a leading budget airline and has moved to a group that includes a leading budget hotel. There are commonalities,” he said.
Harrison, who had also been touted as the next Ladbrokes chief executive, will start at the beginning of September. Headhunters had been looking for a replacement for Parker since the summer, analysts said.
“We conducted a thorough international search and selection process and had a number of high quality candidates,” Habgood said.
Harrison is expected to grow the business while keeping costs to a minimum.
He said: “I am delighted to be joining Whitbread. It is the ideal next step for me.”
THE ambitious chief executive will add Whitbread, the FTSE 100 company, to his list of top jobs when he takes over the reigns in September this year.
In 1996 he was appointed chief executive of Lex Service and led its transformation from a vehicle distribution company into RAC, a strongly-branded, consumer-facing services company with 6.5m members.
During his time at the helm RAC delivered strong growth in a variety of consumer services, which included BSM, financial and legal services, as well as good expansion in business services, winning large contracts. The successful integration of Lex and RAC resulted in a strong rise in profits and a tripling of the share price.
Andrew joined easyJet as chief executive on 1 December 2005. He announced in December this year that he would be stepping down from the budget airline in June. It is believed he took the decision after a row with company founder Sir Stelios Haji-Ioannou.
Since 2000 Andrew has been a non-executive director at Emap, where he chairs the Audit Committee. Prior to Lex Service, Andrew was an executive director of Courtaulds Textiles since 1990.