After a one-over outward nine of 37, 2019 Open champion Lowry gained strokes at 11, 12, 14 and 16 to keep the pressure on McIlroy, but his hopes were dashed with a missed birdie putt on 17.
“There’s still a few scenarios playing through your head. I even though if Shane had made birdie at 17, a three-shot on 18 compared to two shots is different,” added McIlroy.
“I was relieved to see him not hole that.”
England’s Justin Rose, who won this event in 2023, finished on 18 under thanks to a superb eagle at the last.
Russell Henley and Cam Davis came were tied fifth on 17 under, whilst Austria’s Straka struggled on the final day and fell away to end on 16 under.
World number one Scottie Scheffler recorded yet another top-10 finish as he ended on 15 under on his first PGA Tour appearance of the season following a hand injury.