Masters, a former Tesco executive, joined Pepco in 2019 and took over as interim CEO at the end of last month when CEO Andy Bond stepped down for health reasons.
"The decision follows an extensive search process commissioned by the board with the support of an external firm. The board concluded that Trevor was the outstanding candidate for the role," Pepco said.
The group, which listed on the Warsaw stock market last May with a valuation of 5 billion euros ($5.4 billion), also said that finance chief Nick Wharton was stepping down at the end of the month due to health issues.
It said Mat Ankers has been appointed interim chief financial officer.
On Thursday, Pepco reported a 17.5% increase in first half revenue and pledged to "protect prices" for cash-strapped shoppers.
($1 = 0.9224 euros)
(Reporting by James Davey, Editing by Paul Sandle)
