By seeing off the fifth-ranked Thai in straight sets, Tai became the first All-England champion in any discipline from Taiwan in the process.
She was unpredictable but dangerous, with a smash clocked at 223 mph, and overcame the former world champion Ratchanok despite trailing by five points in the second game.
The match also had a twist in the tail. Ratchanok seemed about to level the match at 20-18 in the second game when her sliced smash was called in. But a video replay appeal summoned an image showing the shuttle one inch out and, buoyed by the adrenalin of this escape, Tai snatched three more points and the match, winning 21-16, 22-20.