Although the White Ferns also lost by seven wickets, being bowled out for 129 while England reached 130-3 in the 16th over, Watkin still impressed.
She was sent in at No6 with the instruction to get quick runs, and scored 16 from eight balls, including three boundaries, as she moved across to smack the ball to fine leg.
The White Ferns then changed tactics as Watkin was asked to open the bowling with her off-spinners, and got her team on the front foot with 2-27 from her four overs during the batting power play.
Prize scalps Wyatt and Beaumont both gave up catches to Bates off Watkin to have England worried at 22-2, before wicketkeeper Sarah Taylor (51) and Natalie Sciver (39no) led their recovery.
"I was pretty nervous to have to bowl first," Watkin said.
"I got told before the start of the game and I was thinking about it the whole day.
"But I guess, getting up having to bat first, made the nerves go a little bit before I bowled.
"I just didn't really think they were the best team in the world, I just thought it was a net [session] really, out there, and used that as confidence."
Having not expected to play much during her first White Ferns tour, Watkin said it was "surreal" to follow up her success in the Ireland games by getting to face the world champions England.
"Such an honour to be out there with them. I learned so much from them and put everything into practice.
"Even just being around Suzie, Sophie and Amy [Satterthwaite], I just learn so much off them. Just the simplest things."
Carrying a Whanganui sticker on the back of her bat, the 20-year-old said she is feeling the love from 19,000km away.
"I've had a lot of support from home with coaches, and parents and friends.
"All my family, they're all messaging me every day."
The White Ferns will now face England in three 50-over internationals, starting on Saturday.