Molly-Mae, 20, was a runner-up in this summer's ITV smash hit reality series.
The 'social media influencer', from Hertfordshire, was the first female contestant to enter the Love Island villa.
She was one-half of the show's runner-up couple, alongside boxer boyfriend Tommy Fury.
Molly-Mae's online popularity has soared since her appearance on the ITV show, and she now has more than 3.3 million Instagram followers.
She is also a former beauty pageant contestant, and has been crowned World Teen Supermodel in the UK division of the competition in 2016.
The Love Island star will flick the switch on Leyland's Christmas lights in Hough Lane at 5.30pm on Saturday, November 23.
A spokesman from the Leyland Town Team said: "We are delighted to welcome Molly-Mae to our town for the big Christmas light switch on this year.
"It's fantastic to be able to get her on board for this year's event and we look forward to showing her our wonderful hometown."
The stage will be located outside The Leyland Lion pub (Wetherspoons), where Molly-Mae will greet fans before lighting up the town.
There will entertainment throughout the day, with music from local artists and stalls offering foods from around the world.
Father Christmas will also be visiting the town to say hello to Leyland's boys and girls in his cosy grotto.
Cllr Aniela Bylinksi Gelder, South Ribble Borough Council, said: "I would like to thank the Leyland Town Team for the dedication, work and commitment they give to put Leyland on the map.
"The Leyland Town Team fund raises throughout the year to secure the funds to deliver the Leyland Christmas Festival, including the lights, TV star and live music.
"The council will be supporting this event, with Hough Lane closed to traffic, and by facilitating stalls, Santa’s Grotto, and fairground rides.
"There promises to be something for visitors of all ages.
"I hope we can attract people from all across South Ribble."