He has been chief operating officer at Canadian supermarket Loblaws since January 2007.
Britain's fourth-largest supermarket chain roped in the former Wal-Mart executive to replace Marc Bolland, who is leaving to join Marks & Spencer.
The appointment of a relatively unknown Irishman as CEO surprised industry watchers.
This is similar to the appointment of Mr Bolland in 2006, then chief operating office of Heineken, who was also little-known in the British retail world, much like Philips.
Philips' arrival could speed the release of Bolland, with whom Morrisons is still negotiating a leaving date.
Morrisons finance director Richard Pennycook was on the short list to succeed Bolland. It remains to be seen if he will remain committed to the company after appointment of Philips.
Loblaw's chairman Allan Leighton is understood to have played a key role in the hiring of the new Morrisons CEO.