At the same time, having been chief financial officer (CFO) for six years and acting CEO for the past seven months, Alastair Murray has agreed with the board to leave the business and step down from the board.
Duncan Leggett, group director of financial control and corporate development, will become acting chief financial officer pending a permanent appointment.
Colin Day has also been appointed non-executive chairman of the company.
Whitehouse said: "I’m delighted to become Premier Foods’ CEO and look forward to working with Colin and the board to drive further value from our great portfolio of brands. I’m very encouraged by the improved performance of the business over the last couple of years and see this as something we can build on further.”
Richard Hodgson, senior independent director said: “I am delighted that Colin Day is joining the company as chairman, a role to which he will bring extensive experience at a pivotal time in the company’s history. We are also very pleased that Alex Whitehouse, who has led the successful turnaround of our UK business, has accepted the role of group CEO.
“On behalf of the board I would like to thank Alastair Murray for his outstanding contribution to the business, both as CFO and more latterly as acting CEO, and wish him all the best for the future.”
Premier Foods continued to be referred to as a 'zombie' company by Clive Black, head of research at Shore Capital, in May, as the company posted a £42.7m loss in the year to 30 March 2019.
Darby announced his intention in November to step down as CEO of the business at the end of January this year.