The 2004 premiership-winning Canterbury-Bankstown Bulldogs winger was left with serious leg wounds after the attack at his home at Greenacre, in southwest Sydney, about 6am on Tuesday.
He underwent surgery hours later.
Police were told shots were fired from an SUV that was later found burnt out.
"It's a brazen ambush," Superintendent Rodney Hart told reporters.
Local police have handed the investigation over to the organised crime-focused Raptor Squad.
But a motive remains unclear, with Utai having no clear links to criminal activity.
"This was definitely targeted," Supt Hart said.
"Whether the victim was the intended target or it was somebody that he knows or associates with or is related to, will all form part of the investigation."
Utai had walked out of the home he shares with his wife and children and was about to drive to work when he was shot.
He was "obviously in a fair bit of pain" but able to speak with arriving police who applied first aid, Supt Hart said.
Utai was stabilised by paramedics and then taken to hospital in a serious but stable condition before undergoing surgery.
The SUV involved in the attack was found after being set on fire in Wiley Park, less than a 10-minute drive from where the shooting took place.
Fire authorities extinguished the blaze and the SUV was seized for forensic examination.
Utai starred in the 2004 NRL grand final, scoring two tries as his Bulldogs knocked off the Sydney Roosters 16-13.
The New Zealand and Samoa international played 167 NRL games, joining the Wests Tigers in 2011 and spending three seasons there.
The 2002 Dally M Rookie of the Year finished his NRL career with 85 tries.
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