Ochoa, the world's top-ranked player, also won for the fifth time in six events this year after she came off an astounding 11-shot victory last week at the Corona Championship.
"I think I'm hitting my irons really good and I keep giving myself birdie chances," Ochoa said.
"I did miss a lot of putts today. But definitely, I won the tournament because of my second shots, just being so consistent."
|"I survived. I was tired, mentally and physically tired."|
Ochoa became the first woman to win four straight titles since Annika Sorenstam in 2001. Mickey Wright (1961 and 1962) and Katey Whitworth (1969) also won four straight events.
Sorenstam (2004-05) and Nancy Lopez (1978) share the tour record with five straight victories in events entered, however neither of those came in consecutive weeks.
Tseng started with back-to-back birdies and another at the fifth hole but followed with a bogey at the sixth while Ochoa, who began with a one-shot lead, birdied the third hole and set off on a run of three birdies in a row at the eighth.
Tseng eagled the 10th to keep the pressure upon her Mexican opponent but was undone by birdies at 13, 15 and 17. Ochoa finished with seven pars and a bogey at the 15th, holding on for the triumph.
Ochoa won last week's Corona title in her homeland and followed up by taking her 22nd career title. She has not blown a lead entering the final round since last year.
Ochoa will take a break next week when she sits out the Stanford Invitation Pro-Am, and is scheduled to play again in two weeks in Tulsa, Oklahoma.
"I survived. I was tired, mentally and physically tired," Ochoa said.
"I didn't have my legs at the end for the last two or three holes. I'm just glad I hung in there and was able to finish strong. For sure, I'm ready to take a break."
With the pressure mounting, Tseng struggled down the stretch but still managed the best showing of her career with her second-place finish.
"I almost caught up, but on the last couple of holes, I just made some bad putts," Tseng said.
"I'm not really disappointed, because I think it was a good experience.
"I still have a long way to go and I want to keep learning and learning."