Seth Jones and Oliver Bjorkstrand added a goal and an assist each for Portland (53-12-3), while Taylor Leier chipped in with four assists. Brendan Burke made 27 saves to get the win.
Joe Hicketts and Logan Nelson had the goals for Victoria (33-29-7), which got 39 saves from Coleman Vollrath.
Portland opened the scoring at 3:34 of the first period when Bjorkstrand fired home his 29th of the season right off a faceoff and Winterhawks added to their lead at 9:48 of the second as De Leo tucked in his 15th of the year on a 3-on-1 rush.
Jones made it 3-0 with his 13th goal of the season at 13:08 on a delayed penalty.
Nelson got the Royals on the board in the third period as he buried his 13th of the campaign at 7:47, but Portland regained its three-goal advantage on De Leo's second of the night just over three minutes later.
Victoria pulled within two late in the third period on Hicketts's third of year before De Leo completed the hat trick into an empty net.