The Championship club say they fought off Super League interest for the exciting player who has shone for the Cumbrians this term, scoring 15 tries and earning a Scotland call-up.
Walmsley, 22, recently won the Betfred Championship Entertainer of the Year award, thanks to some of his eye-catching finishes and dazzling performances.
“I’m excited to join the Panthers for 2022,” said Walsmley, who is also a prolific goalkicker who was on the books at Newcastle Knights and South Sydney Rabbitohs in the NRL.
“It’s a squad full of exciting players which can produce some quality rugby for the fans to enjoy.”
Halifax coach Simon Grix, looking to improve on this year’s third place finish in 2022, said: “Lachlan has had a great year, backing himself to get over here with the ambition to play Super League.
“He has been a standout performer this year, scoring tries out of nothing and showing X factor with some freakish finishes.
“It’s a real coup to have got him over the line as some big clubs were circling.
“I look forward to aiding in his development and watching the competition for places bring out the best in him.”
Toulouse have made former Huddersfield hooker James Cunningham their first recruit for their Super League campaign.
The 27-year-old began his Super League career with home-town club Hull before going on to play for London Broncos and Toronto Wolfpack.
Cunningham was signed by Huddersfield on a two-year contract 12 months ago but did not play for them in the second half of the 2021 season and was released by mutual agreement.
“I’m really happy to join Toulouse,” he said.