The 30-year-old, who won the season-ending Tour Championship, worth $15million, last month, finished top of voting amongst fellow players.
In all, McIlory had three Tour wins during the 2018/19 season, also landing the Players Championship in March and the Canadian Open in June.
McIlroy also managed two top-ten major finishes, at the US Open and the PGA Championship, though he missed the cut at the highly-anticipated Open Championship on home soil at Royal Portrush, and once again failed to complete a career-slam by winning The Masters at Augusta.
American Brooks Koepka had looked to be favourite for the award, having won the PGA Championship and finished in the top four at all three of the other majors.
The win is the third of McIlroy’s career, with the previous successes coming in 2012 and 2014.