Ochoa, who was playing in her first event of 2008, eventually carded a 20-under-par 268 for the tournament to be crowned the 'Champion of Champions,' joining Phil Mickelson, who holds the men's Champions title.
"I came here prepared to win and I did it," Ochoa said.
"I practised really hard in the off-season and I knew I could do it. I have faith in my game and hopefully this will be a great year.
Swedish star Sorenstam took runner-up honours with a solid 71 to end the tournament at nine under-par 279, two ahead of American Paula Creamer, who won the Fields Open last week.
America's Laura Diez came fourth while another American, Stacy Prammanasudh, and veteran Australian Karrie Webb, tied for fifth.
After torrential rain caused a one-hour delay on the final day, Ochoa shattered any hopes the chasing pack had of catching her by making birdies on the third and fourth holes while playing partners Sorenstam and Creamer only managed pars or worse.
Rain can't stop Ochoa
The birdies stretched the 26-year-old's lead to 10 strokes and there was no looking back.
Sudden downpours forced players off the course two more times, but failed to break Ochoa's focus as she wrapped up victory with a par on the last for victory in her first event in three months after a long off-season layoff.
At one stage some of the greens were completely flooded, and only the exemplary drainage system at Tanah Merah Country Club allowed the tournament to finish, with the final group taking eight hours to complete their round.
Ochoa was the only player to shoot four rounds under 70, and took home a cheque for $300,000 for her win.
Only winners from the LPGA Tour, the Ladies European Tour and tours in Japan, Korea, Australasia and Asia, were eligible to play in the $2 million Champions tournament.