Ha Na Yang from Korea eased away from the field with a 19-under par total to claim her second LPGA victory this year.
She finished second four times in her rookie season but this year won in Florida last month and continued that strong form into Asia and is right in the frame for a spot at the Olympics. She finished with an eagle on the par five 18th when she hit a fairway wood over the lake guarding the green.
"That was a mistake actually," she revealed. "I was just trying to take it right of the bunker but missed. I was saying 'don't hit the tree, just get on the green' and when it landed I was like 'what an amazing shot'."
Ko started the year well then took a week off before Singapore as she worked through her game with swing coach David Leadbetter.
"I think it's never perfect and I'm pretty sure there will be times where it will be close to perfect and we'll work towards that," she said. "I don't know if the swing can ever be perfect or have a perfect round but I felt like I struck the ball better the last two days, so that was a good sign."