Deniskin is currently deputy chairman of Eurasian Resources Group's board of production.
He will take over in April, when acting CEO Sergey Ermolenko will leave the company's board and go back to his old job of general director.
Petropavlovsk also announced it had appointed Fincraft Holdings director Bektas Mukazhanov to the board.
Cyprus-registered Fincraft owns 20% of Petropavlovsk, making it the largest shareholder. Kazakhstan's finance ministry links entrepreneur Kenges Rakishev to the firm.
Petropavlovsk has had a tumultuous few quarters, with the shareholder revolt to kick fellow founder Peter Hambro off the board, Maslovskiy's departure and then over Christmas the surprise sale by chief agitator Renova Group of its entire holding in the company.
Away from the boardroom drama, the gold miner's results have remained steady.
Chairman Ian Ashby said the company had looked long and hard for a suitable CEO.
"[Deniskin's] appointment follows a comprehensive external search and has the full support of our major shareholders (Fincraft Holdings, Sothic Capital, the D. E. Shaw group and M&G Investments)," he said.
"Roman brings all the necessary experience and leadership attributes required as we enter a new phase in the company's history with the completion of our POX development and the start-up of our underground mining operations."