The Council attributed the healthy numbers to holding the switch-on and traditional Christmas market in one place, on St Peter's Hill, for the first time and the extra events that were put on.
While waiting for the switch-on, visitors were entertained by characters from this year's panto, Peter Pan, an ice sculptor at work creating a reindeer, an enormous snow-globe and even tap dancing turkeys.
Extra sparkle was added to this year's switch-on, courtesy of SKDC, with white lights on the large trees on St Peter's Hill and fireworks for the finale. The event was organised in conjunction with Grantham Events Group.
"We have had a huge number of complimentary comments," said Cllr Nick Robins, South Kesteven District Council's Cabinet Member for Retail and Visitor Economy.
"It was a great community effort. We were really pleased with the way things went and the number of people who came along. Retailers were very happy with the day and the focus on St Peter's Hill worked extremely well."
Stallholders' comments were very positive, he said, quoting Sally Rozier from Felicity-Ann Bags, Crafts & Textiles, who contacted SKDC markets organiser Miki Gregory to say: "A huge thank you to you and your team! The Grantham Christmas Market was amazing!
"My stall did very well, my neighbouring stallholders were great and the people of Grantham seemed to enjoy all of it! The entertainment was superb and the lights and fireworks were wonderful!"
Ann Hatcher, from Addaction, added: "I just wanted to say thank you for yesterday, I felt the event was extremely well organised and I had a really thoroughly enjoyable day. I felt extremely supported by staff at the Guildhall, who were so polite and helpful."
Darryl Blair from event fundraisers Grantham Disabled Childrens' Society (GDCS) confirmed a fantastic day's fund-raising, contacting SKDC to say: "I just wanted to write and say a massive thank you to you and your team for the work that went into yesterday's Xmas light switch. It was a fantastic day."