Larrazabal was among a handful of players who were forced to play the final few holes of the third round early on Sunday after bad weather at Jack Nicklaus Golf Club Korea in Incheon caused delays of more than two hours the previous day.
He was able to clinch victory by two shots in a tight battle at the tournament, which saw the DP World Tour return to Korea for the first time in 10 years.
"Only probably my family and my team knows how tough the last 10 months have been," Larrazabal said after his win.
Larrazabal roared back after dropping his first shot of the day at the tenth, making four birdies in the next five holes to open up a three-shot lead.
He then safely parred to complete a closing 67, finishing the tournament on 12 under par and claiming an eighth DP World Tour title.
The Spaniard went into the final round one shot off the lead, having bogeyed the 17th when he returned to complete his third round on Sunday morning.
"Yesterday was a battle," he said. "I actually didn't look at the leaderboard too much yesterday because I knew it was a long road."
He took advantage of both of the front nine's par fives - the third and seventh - in round four to share the lead at the turn.
"But I love to compete, I love to fly out here, to see all these young guys hitting it miles and try to beat them," said Larrazabal.
"And that's what makes me the happiest guy in the world."
Denmark's Marcus Helligkilde finished alone in second on 10-under, one clear of home favourite Park Sang-hyun, Spain's Jorge Campillo, Dutchman Joost Luiten and Scotland's Scott Jamieson.
