Phil Irons, the father of the 32-year-old surfer, confirmed his son's death Tuesday. The cause of death was not immediately known.
The younger Irons was found dead in a hotel room in Dallas, where he was on a layover en route to his home on Kauai. He was returning from Puerto Rico, where he was to have competed in the 2010 Rip Curl Pro Search.
Employees at the Grant Hyatt Hotel DFW Airport found the body and called Dallas-Fort Worth International Airport police at 9:44 a.m.
Public Safety officials said the guest had checked in Monday and had died of unknown causes.
The Tarrant County Medical Examiner will perform an autopsy Wednesday to determine the cause of death.
Irons was expected to compete against two Australian surfers in his first heat Saturday, but didn't show up, much to the confusion of commentators.
Rip Curl officials said Irons withdrew Sunday, citing an illness he contracted during an event in Portugal.
Family members from Kauai were headed to Dallas late Tuesday.
Irons was scheduled to compete in the Vans Triple Crown of Surfing in Hawaii, which is scheduled to begin next week. He was a four-time winner in the prestigious event.
"The thing that I think many of us appreciated the most about Andy was that he was an incredibly real person," Triple Crown spokeswoman Jodi Wilmott said. "Where a lot of champions in sports and celebrities become very guarded and you just wonder sometimes if you're really seeing who they are, you've got Andy Irons 100 percent of the time."
Wilmott said Irons was a passionate person and an incredibly competitive athlete.
"He reveled in competition and in stepping up to the plate and I think that's something in sport that anybody can admire," she said.
Irons claimed the world championship in 2002, '03 and '04, becoming an icon in the surfing world. He was also revered on his home island of Kauai, along with his younger brother Bruce, also a pro surfer. Irons was raised and learned how to surf on the tranquil and scenic North Shore, where he was married three years ago.
In a video posted by his longtime sponsor, Billabong, Irons talked about his first wave he ever caught.
"I thought right then, 'This is the coolest thing in the world.' ... I literally will never forget that wave," Irons said.
The Irons family in a statement thanked the surfer's friends and fans and requested privacy "so their focus can remain on one another during this time of profound loss."
Billabong posted a tribute page on its website, which includes a photo and video of Irons. In the clip, Irons talks about making a comeback and fighting "inner demons."
Billabong called Irons one of the "greatest surfers of our time."
"More than that, he was a much loved son, a devoted husband and a soon-to-be father. The thoughts of all Billabong employees worldwide are with wife Lyndie and Andy's family at this most devastating time," the company said.
Irons' wife, Lyndie, is pregnant and scheduled to give birth to their son and first child in December.
Billabong tribute to Andy Irons: http://www.billabong.com/us/
AP writers Danica Coto in Puerto Rico and Terry Wallace in Dallas contributed to this report.