Emmerdale star Dominic Brunt - who plays vet Paddy Kirk in the soap – carried out the big switch on this afternoon, illuminating the 30-foot tree and the giant Christmas lettering.
He was joined by members of basketball team Yorkshire Dragons and The Sing Space Choir.
Today also saw the first day of what will be six weekends of Christmas markets at the Halifax landmark.
They will take place every Friday, Saturday and Sunday from now until December 20, opening 10am and 6pm on Fridays and Saturdays and between 10am and 4pm on Sundays.
Thousands of visitors are expected to explore the courtyard before Christmas, with last year’s markets welcoming around 276,000 people.
CEO of The Piece Hall Trust Nicky Chance Thompson said: "We are incredibly proud to be attracting so many visitors to Calderdale this Christmas while also bringing our local community together in this magnificent, historic setting at the most magical time of the year!
“Our traditional festive experience, complete with beautiful tree, vintage carousel, and live music, alongside the showcasing of our incredible independent shops and local market traders, creates a truly unique festive destination."
5. 7 festive photos as Christmas lights go on at Halifax's Piece Hall
The 30-foot tree is now illuminated Photo: Ellis Robinson
6. 7 festive photos as Christmas lights go on at Halifax's Piece Hall
This weekend is the first of six weekends of Christmas markets at The Piece Hall Photo: Ellis Robinson
7. 7 festive photos as Christmas lights go on at Halifax's Piece Hall
The huge tree, all lit up Photo: Ellis Robinson