The British chart topper will join Ginger, Baby, Sporty and Scary as they play a string of near sold-out stadium shows around the UK.
The Spice World tour starts tomorrow in Dublin, Ireland before gigs in Cardiff, Manchester, Coventry, Sunderland and Edinburgh.
The trek will wrap up on June 15 after three nights at London’s 90,000 capacity Wembley Stadium.
Speaking on stage at her intimate War Child BRITs Week Together with O2 gig, which had been postposed due to her poor health, Jess said: “It’s a big week for me.
“I’m supporting the Spice Girls on their arena… no stadium tour and my new single comes up on Friday.”
For her latest track One Touch, Jess has teamed up with DJ and producer Jax Jones.
Jess previously said she only signed up to the tour in a bid to befriend the Spice Girls.
She joked: “The whole point of me doing this is so that I can hang out with them.
“I’m not doing it for any other reason!”
Jess added to Hits Live: “I’m so excited.
“I wasn’t allowed to tell anyone. It was an amazing moment!”
Earlier this week Geri Horner unveiled an epic image overhaul ahead of the shows.
The starlet, who was left red-faced after Mel B recently revealed they had enjoyed a lesbian fling in the 90s, has gone back to her ginger roots for a stunning L’Oreal campaign.
Slipping into an elegant white gown, Geri looks sensational as she poses for the new pics.
Beaming away, the pop beauty’s long locks blow freely in the breeze reflecting in the light.
