There were echoes of Emma Raducanu after the 27-year-old qualifier, Britain’s sole representative on day one, beat Russian Margarita Betova 6-3 6-3.
The world number 199 may be unlikely to emulate Raducanu’s fairy-tale title win two years ago, but she still secured a near-£100,000 pay day and a high-profile second-round match against Olympic champion Belinda Bencic.
“It’s going to be a tough match for sure,” said Miyazaki.
“But I guess the good thing is I’ve seen her play plenty of times and she probably doesn’t know much about me.”
While the other six British players in the main draw had the day off, Miyazaki took on the experienced Betova, who was playing under a protected ranking after coming back from having a child.
Miyazaki, who moved to London aged 10 but only changed allegiance from Japan last year, overcame an early break and won six games in a row to take control.
With fellow Brit Jodie Burrage cheering her on, Miyazaki finished the job on her second match point to win in an hour and 20 minutes.
Miyazaki, whose only previous grand slam appearance came when she lost in the Wimbledon first round in 2022 as a wild card, added: “I’ve enjoyed the atmosphere here.
“I was really grateful for the support from Jodie and everyone, and it definitely helped me out.”