Runners, some wearing blue Santa outfits in support of Everton, set off from the waterfront for the 5K race.
Organiser BTR Liverpool said it will be a "huge boost" to take the title back from Las Vegas after four years.
Final numbers are being counted but Las Vegas' Santa Dash had fewer than 8,000 people on Saturday, BTR Liverpool said.
This year's fun run featured the biggest Mini Dash 1K for children aged under 12 with 750 taking part.
BTR Race Director Alan Rothwell said: "All our Santa Dashers really got into the spirit of the day, with some very creative costumes.
"It is very fitting that we have regained the World Santa Challenge title on our 10th anniversary.
"We are absolutely thrilled. We are now not only the UK's biggest festive fun run - but now also the world's."
About 8,500 people donned Santa suits at Liverpool's 10th annual Santa Dash - attempting to win the World Santa Challenge for having the most runners.