Watkins hit an unbeaten 89 off 58 deliveries to continue her dream run with the bat as the White Ferns cruised to a 52-run win over India in the first semifinal at Trent Bridge.
New Zealand posted 145 for five off 20 overs, then restricted India to 93 for nine as Sian Ruck and Amy Satterthwaite took two wickets apiece.
They will face either tournament favourites England or Australia in Sunday's final at Lord's, after the two rivals clash in the second semi early tomorrow.
It was New Zealand's fourth consecutive victory after they brushed aside Australia, West Indies and South Africa in pool play to stamp themselves as title contenders.
"It was good to put a complete performance together, it was something we haven't done throughout the tournament so to pull that out today was really pleasing," Watkins said.
"Obviously we're rapt to be at Lord's, it's the home of cricket and we're just stoked to be there, so watch out for us."
Having just taken over the captaincy from the retired Haidee Tiffen, Watkins was the dominant figure. She hit 10 fours and two sixes in her innings, which topped England batter Claire Taylor's tournament high of 75 against Sri Lanka.
She moved past teammate Suzie Bates as the tournament's leading runscorer with 198 at an average of 99, which began with an unbeaten 73 in game one against Australia.
"It was just one of those days, whatever I did seemed to come off. The cricket gods are with me at the moment and I'm loving it," Watkins said.
Watkins arrived in the second over and quickly took control after the early departures of Lucy Doolan and Bates.
She reached 50 off 40 balls, with the lofted square drive earning the bulk of her early boundaries off the Indian seamers.
When Satterthwaite was run out by a Mithali Raj direct hit for 10, and Nicola Browne stumped for five off spinner Prijanka Roy, the innings teetered slightly.
But Watkins helped add 52 off the final five overs, including a six off the final ball, while allrounder Sophie Devine contributed an eight-ball cameo of 14 not out.
New Zealand were a slick unit in the field with some polished catching and a brace of run outs.
Left-arm seamer Ruck, New Zealand's bowling find of the tournament, had India on the ropes early in their chase.
Her opening four-over spell of two for 18 included a sharp catch by Devine, before she bowled Harmanpreet Kaur first ball.
A Satterthwaite run out off her own bowling had India in strife at 42 for four after 10 overs, then she removed the key Indian batter Raj for 20 to ensure there was no fightback.
A Sara McGlashan direct hit run out then summed up a memorable day at the office for the Ferns.
