The Scotland international joins Gareth Taylor's squad on a deal until the end of the 2025-26 season.
She arrives at the Reds with a wealth of Barclays Women's Super League experience having also represented West Ham United and Manchester United before moving to Spurs in 2023.
On the national stage, Thomas has delivered a goal rate of nearly one-in-two for her country: 21 strikes in 52 senior Scotland appearances since debuting in March 2020.
"It means a lot. It's a really exciting time for me and I'm really excited to be here," she told Liverpoolfc.com in her first interview at the AXA Melwood Training Centre.
"I think it's the right fit, right now in my career. Even though it's a short loan, I'm really looking forward to be here and help this team climb the table where they deserve to be."
Watch Thomas in action with Liverpool - match ticket details here
Born in England, from an early age Thomas grew up in the USA and went on to star for the Charlotte 49ers in college soccer.
Her professional career began in France with a single season at Le Havre, before establishing herself in the WSL, initially at West Ham.
A two-year stint with the Hammers from 2019 was followed by a spell at Manchester United of the same timeframe.
Thomas then switched to Tottenham and brought up a century of appearances in the English top flight in March 2024.
The 29-year-old, who will take the No.31 shirt, added: "Results are important and that's how you get points on the table, but you look at Liverpool's performances they have put in this season, I feel they have put strong performances in.
"It's just about getting over the line and picking up points. I've got full faith in this team.
"I wouldn't have joined if I didn't think I could help and I didn't think it was a successful project going forward."