Seven-time world champion Nicol took just 39 minutes to down King 11-6, 11-8, 11-5 and will meet either second seed Laura Massaro of England in the final.
Massaro held her own against compatriot Alison Waters before registering an 11-5, 12-14, 11-3, 11-8 win.
Nicol, who wore an all-black outfit, including the headband, began well by taking an 8-4 lead in the first set. She dropped just two more points en route to winning it 11-6.
The lanky Kiwi player, however, came back strongly in the second set to take a 5-1 lead. But Nicol showed why she is the world’s best by playing a superb game to level the score before going on to win 11-8.
The third set again saw King taking a 3-1 lead before Nicol upped the ante with some good shots to win 11-5.
Nicol admitted that she played her best squash on Sunday “although King was on fire”.
“She gave me a good fight in the first two sets. I knew I had to bring out my best to get her,” said Nicol.
“King played really well but she could not maintain her form.”
Nicol said she is looking forward to the final.
“I don’t know who I will face in the final but I’m happy with the support shown by the fans here,” she said.
Asked why she wore all black, Nicol explained: “I have two sets of attires … either white or black.
“I chose to wear black because King was wearing white.”
King was disappointed with herself for failing to capitalise on the two leads she had.
“I only played well in patches but Nicol played exceptionally well,” said King.
Meanwhile, in the men's event, world No.1 and defending champion Nick Matthew of England swept aside compatriot Peter Barker with an 11-3, 13-11, 11-6 win.
It will be an all-English final after second seed James Willstrop proved too strong for India's Saurav Ghosal with an 11-8, 11-8, 11-5 win.