Mr Cadbury is leaving just a year after joining the Leeds-based electronics distributor.
His departure comes hot on the heels of the exit of Premier’s former chief executive Harriet Green, who left to join tour operator Thomas Cook in May.
The two events are not thought to be related.
Mr Cadbury, who joined Leeds-based Premier from retailer Dixons, was lured by the opportunity to return to the consumer sector in a FTSE 100 listed company.
Premier said Mr Whiteling, who left last August to join private equity-backed vending machine company Autobar Group, will rejoin the company in an expanded role that encompasses IT as well as finance.
Mr Whiteling’s departure was seen as a loss to Premier when he left last year as he was part of the core team alongside Ms Green and current chief executive Laurence Bain.
Premier said the date of Mr Cadbury’s departure and Mr Whiteling’s appointment will be announced in due course.
The transition period is expected to be completed by the end of October.
The Premier board said it was delighted that Mr Whiteling has agreed to re-join the company, having previously spent five years as finance director.
It added that he played a key role in developing the company’s current strategy and worked closely with Mr Bain in its implementation.
Mr Bain said “I would like to thank Nicholas for his contribution during his time with us and I am very pleased that Mark has agreed to re-join us.
“Mark’s considerable knowledge of the industry in which we operate, the business and its people will allow a seamless transition.
“I also know that Mark and I will work well together as part of the wider leadership team.”
Mr Cadbury will join Whitbread as group finance director later this year.
Premier said it wished him every success in his new role and thanked him for his contribution during his time with the company.
Mr Cadbury joined Premier in 2011 after working at Dixons Retail in a variety of roles
These included three years as Dixons’ finance director.
Mr Cadbury will succeed Christopher Rogers, who is taking over the role of managing director of the group’s Costa Coffee chain of shops.
Mr Cadbury said: “I feel privileged to be joining Whitbread and to be part of the management team at an exciting time in the company’s development as it seeks to strengthen its presence, both in the UK and overseas.
“I look forward to the opportunity of using my retail consumer background and international experience to help drive its ambitious growth agenda.”
Whitbread’s chief executive Andy Harrison said the group conducted a thorough international search before choosing Mr Cadbury.
“Nicholas has experience as finance director in two different multi-national PLCs,” he said.
“In addition, he has 18 years’ experience of working in a multisite consumer business across a broad range of roles at Dixons, including commercial director for PC World and managing director for PC City, Italy.”
He added that Mr Cadbury’s experience will be highly relevant to Whitbread as it realises its “ambitious plans” for the business.
Whitbread’s chairman Anthony Habgood said Mr Rogers had made an “outstanding contribution” to the development of Whitbread during his time as finance director.
“We are fortunate to have his continued presence at the board table as managing director of Costa Coffee,” he said.
Following the news Premier’s shares fell 3.5 per cent yesterday, down 6.7p to 186p.
Whitbread’s shares fell 1.2 per cent to close down 26p at 2100p.
Whitbread is the UK’s largest hotel and restaurant group and operates budget hotels, restaurants and coffee shops.
Its brands include Premier Inn, Beefeater, Brewers Fayre, Table Table, Taybarns and Costa.
The leisure giant has outlined five-year growth milestones to 2015/16 to increase the number of Premier Inn UK rooms to at least 65,000.
It also aims to add 80 to 100 new restaurants and to nearly double the size of Costa with global system sales of £1.3bn and 3,500 stores worldwide.
In the year to March 1, Whitbread reported an 11.2 per cent increase in group revenues to £1.78bn and an 11.3 per cent increase in underlying pre-tax profits to £320.1m.