Designer Miss Gabbidon, 26, won the investment of Alan Sugar after winning the BBC One competition in December.
This weekend, she set up a pop-up shop at Trinity Leeds after the online launch of her business Sian Marie's SS19 range.
Watch the brilliant moment lady busts out amazing dance moves in Leeds TrinityBut she wanted the event to "make people feel good", so brought along some DJs, put on hair and make-up sessions and invited carnival style dancers, as well as meet-and-greets with some of her friends from The Apprentice.
Miss Gabbidon, of Alwoodley, said: "It's been amazing. It was literally madness, it was like a massive street party.
"We had an 87-year-old lady who was getting down, then went to bingo and came back for more."
In Photos: Leeds Apprentice winner Sian Gabbidon reveals stunning new swimwear rangeThe pop-up was placed near the centre's store for Leeds-based brand Marks and Spencer, a fitting location for a woman who loves her home city.
She said: "Throughout the show I was a massive advocate of Leeds.
"For me, I wanted to have a celebration with my Leeds people.
"I couldn't have chosen anywhere other than here to do it."
She added: "I do love London, but you get everything in Leeds."
Shoppers got the chance to meet Miss Gabbidon along with some of her fellow candidates from The Apprentice, including Tom Bunday, Rick Monk, Jackie Fast, Khadija Kalifa, Jasmine Kundra, Kayode Damali, Alex Finn and Kurran Pooni.
The entrepreneur, who has predominantly promoted her business online, decided to bring the pop-up to people so they could properly see her products, which will be appearing at retailers soon.
"It's about the experience," she said. "This is my brand, it's a bit of a translation of me. It's about making people feel good."
Miss Gabbidon grew up in Whinmoor and went to Corpus Christi School in Halton Moor, then Garforth Sixth Form where she studied textiles, art and English, before a degree in Fashion Design with Marketing and Production, graduating from Huddersfield in 2014.She said: "I've always wanted to do something like this, I love design, even just a pop-up is a dream."
Now things have changed, as her triumph in the competition came with a £250,000 prize money for investment.
"It's just a dream come true," she said.