Mulroy finished the 72-hole tournament at 19-under 269 for his first European Tour title. George Murray had a bogey-free 5-under 67 Sunday and finished second at 17-under for the tournament.
Mulroy had jumped into the lead at the Dunhill with an 8-under 64 Saturday. He faltered slightly early Sunday with a bogey at the second hole but made the turn at 1-under after birdies at the sixth and eighth holes.
He added birdies at 10 and 13 before a bogey at 14 pulled things closer. Murray dropped his second shot on the par-5, 598-yard 15th hole to within 10 feet and made the eagle putt to tie for the lead.
But while Murray had pars the rest of the way, Mulroy was able to put the tournament title away with birdies at 15 and 16.
Texas principal bans speaking Spanish, stirs controversy
Exploding whale video goes viral on Internet