The life-size, 5.5m long model of Thomas is spending eight weeks in his new home before returning to The Isle of Sodor.
The Fat Controller will also be paying regular visits to St Johns in the city centre to sit with Thomas and meet shoppers.
The Albert Dock family attraction Mattel Play! Liverpool are behind the event.
Zachary Roberts-Kendall, commercial manager for Mattel Play! Liverpool, comments: “We hope children and parents who grew up with Thomas will enjoy coming to St Johns to see him and stop for a photo.
“The Fat Controller will also be making regular appearances to meet Thomas fans young and old.
“Thomas is easy to find – just enter St Johns at the entrance under the Radio City Tower, then turn left and he’s located 100 yards ahead, after the lifts.”
Visitors to the shopping centre can see Thomas the Tank Engine during St Johns’ normal opening hours, Monday to Saturday, 9am-6pm and Sundays, 11am-5pm, until April 10th.