Jess Silk says she "thought someone was taking the mick" when she received a message through her bandcamp page from Bragg himself inviting her to play at the festival next month.
She then had to go through an agonising six-week wait until she was allowed to formally announce the show, which forms part of the 'Radical Round-Up' at the festival's Left Field Stage.
The 26-year-old from Kingswinford, said: "When I was contacted at first I thought someone was taking the mick, and I was amazed when I replied to the message and it turned out to actually be from Billy Bragg.
"I had to keep it under my hat for about a month and half, which was really difficult, and it was a relief when I was finally allowed to announce it."
She said Bragg – who she often gets likened to – was "definitely an influence" and added: "Glastonbury is such a huge festival and by playing there it means I get to cross two off the bucket list in one go – a gig with Billy Bragg and it's at Glastonbury."
Jess, who released her latest EP in September, says she has loved getting back to playing live gigs after lockdown.
She performed at her first festival of the year in Doncaster this past weekend, and a packed schedule over the coming months includes an appearance at Katiesfest in Stourbridge on May 22.
The Glastonbury show takes place on June 25, and also features Yard Act, Billy Nomates and Kam-BU.
Find Jess Silk on Facebook for more details.