The store will be Tesco's first large multi-storey high street Superstore, located on the junction of Hanover Street and Seel Street. The Tesco store houses food and drink, clothing, DVDs, CDs and electronics.
Tesco said that the store was not part of a plan to take its Superstore format into high streets and city centres.
To promote the store, Chegwin will work in Tesco uniform stacking shelves, helping customers and working on the ‘Chegout'. He will also be giving a customer the chance to win £1000 in Tesco giftcards with a game.
Radio City will also be in-store following the launch ceremony giving customers chances to win the latest concert tickets plus instant Tesco prizes.
The 29,000-sq-ft Tesco Superstore is part of the second phase of the £1bn Liverpool One development.
The complex, which opened last year, already has large John Lewis and Debenhams stores. Other retailers to open in the centre will include Jigsaw, Cafe Nero and Topshop.