The 28-year-old sunk three birdies against a lone bogey to return with a winning total of 11-under 277 to defeat USA's Johannes Veerman (71) by one-shot at the Linkou International Golf and Country Club.
With the victory Sandhu took home USD 90,000 including a two-year winner's exemption on the Asian Tour.
"I'm still shaking from the last putt but now that I'm thinking about it, it is absolutely amazing," said Sandhu after becoming only the second player from India after Gaganjeet Bhullar to win the Yeangder TPC.
"I'm proud of myself that I was able to focus on my own my game. I was just trying to hit the next shot the best that I could and I won," added Sandhu, who is also the second player after Jazz Janewattananond to win an event without a full Tour card.
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"I thought about the win after I hit the drive on 18 because the guys were two shots back. But then my second shot ended up in the bunker and I told myself that you can't let that thought enter your mind. It does cross your mind but I was pretty sure I had to come back to the present.
Local star Lu Wei-chih posted a 72 to miss out on the chance to win the Yeangder TPC for the second time in his career.
Lu fired four birdies against as many bogeys to claim his best result since winning the 2016 Mercuries Taiwan Masters.
Sandhu kept a cool head to romp to his first Asian Tour victory. The win was a huge lift in his career as he missed out on a Tour card at Qualifying School earlier this year.
Veerman, also searching for a first Asian Tour victory, almost forced a play-off when his eagle chip on the 18th hole hit the pin. He settled for runner-up, the second time in his career on the Asian Tour.
Lu, who underwent a brain surgery in 2012, was disappointed to miss out on a grandstand finish when he bogeyed the par-three 17th hole due to a poor club selection.