She carded a 4-under 68 to win the event by a stroke over Ward. Ochoa finished at 16-under-par 272 at the Ironhorse Course at Vanderbilt Legends Club.
Ochoa, who became the first Mexican player to win an LPGA Tour event, nearly missed out on a celebration thanks to some wild play on the par-5 closing hole at the Ironhorse Course.
Ochoa was able to pull three clear coming to the 18th but Ward made things very interesting in the group ahead of Ochoa. Ward found the fairway off the tee, then knocked a 7-wood to 6 feet with her second. She rolled home the eagle putt to get within one shot of first place.
Ochoa also landed in the short grass off the tee but never looked comfortable over her second. She hit a fairway-metal into the bank the guards the 18th from water and rolled back toward the pond. Ochoa's ball stopped short of the water but she had to get down in three for the win.
Her chip came up 12 feet short and Ochoa ran her birdie try 2 feet past the hole. She tapped in the par-saving putt to join Karen Stupples and Jennifer Rosales as first-time winners on this year's LPGA Tour campaign.
'I've been waiting for this moment for a long time,' said Ochoa, who pocketed $135,000 for her first LPGA Tour win. 'I cannot express my feelings. This is for my family.'
Ward posted a 5-under 67 for her 15-under-par 273 total.
Stacy Prammanasudh also fired a 5-under 67 on Sunday and took third place at 14-under-par 274. Pat Hurst, who shared the second-round lead with Ochoa, only managed a 2-under 70 in the final round but came in fourth place at minus-13.
Ochoa began Sunday's final round with a one-shot lead and held that advantage throughout the front nine. She tallied birdies at three, five and nine but Ward flew into the race with four birdies of her own during the same holes.
When Ochoa lipped out a 5-foot par save at the 13th, she was tied for the lead with Ward. During the time Ochoa bogeyed 13, Ward had her own problems on the par-5 14th.
Ward's approach hit the green but spun back into the fairway. She chipped to 6 feet but missed the par putt, falling one behind Ochoa. Ochoa followed Ward's mistake at 14 with a 15-foot breaking birdie putt of her own to go two ahead.
Ochoa hit a safe tee ball at the par-3 16th but helped herself when she holed the 22-footer for birdie and a three-shot margin.
Hurst cut the lead to one with three birdies in her first six holes on the back nine, but fell off the pace with back-to-back bogeys at the 16th and 17th holes.
The tournament was Ochoa's to lose until Ward's eagle. Ochoa had a good look at birdie at the 17th but missed. She was able to get up and down in three to hang on for the win.
Ochoa received some extra inspiration early on Sunday. In the morning, her family found out Lorena's brother Alejandro reached the summit of Mt. Everest.
'It was difficult for him,' said Ochoa, who won 12 times in her career at the University of Arizona. 'I thought about him my whole round. I admire him very much and thanks for everything.'
For Ward, the runner-up finish was her highest this season and the eagle at 18 was enough to get her into second.
'I just had a great yardage for a 7-wood back to the pin,' said Ward, a two-time Solheim Cup player for the Americans. 'I couldn't believe it got that close. It's a fun way to finish.'
Dorothy Delasin shot a 4-under 68 on Sunday and took fifth at 11-under-par 277.
Mi-Hyun Kim, who was in second place after three rounds, struggled to a 3-over 75 on Sunday and tied for sixth place. She joined Paula Marti, who fired a 7-under 65, and Gloria Park, who posted a 69, at 8-under-par 280.