The British number two will take on Belgium’s Kirsten Flipkens in Sunday’s final as she aims to win her third WTA title.
“I’m very happy to be in the final. I’ve played Kirsten a few times and she’s very experienced,” said Watson.
“It definitely won’t be easy so I’m going to have to bring my A-game tomorrow.”
Flipkens knocked out British number one Johanna Konta 6-3 6-7 (2-7) 6-1 in the quarter-finals.
Meanwhile, British number three Naomi Broady lost 6-4 6-3 to sixth seed Eugenie Bouchard in the Malaysian Open semi-finals.
Broady has withdrawn from the Indian Wells tournament, which gets under way on Monday.
I'm so sad to say I've decided to withdraw from Indian wells. I'd have to play on Monday in qualies and don't arrive til Sunday PM
— Naomi Broady (@NaomiBroady) March 5, 2016