Smith has been toiling away in the FIA Formula 3 Championship for the past two years with Van Amersfoort Racing.
This year, he scored a career-best fourth at the British Grand Prix but was otherwise outside the top 10 in every race.
Smith’s move puts him on the path towards the IndyCar Series, where he’ll race against compatriot Jarrod Hughes.
Smith got his first taste of IndyCar and Indy NXT at the season finale at Nashville Superspeedway.
“I am excited to compete in America and am up for the challenge. It was a great opportunity to watch the final Indy NXT race in Nashville with HMD,” Smith said.
“The series is competitive, and racing on ovals will be a new experience for me, but I’m excited to get behind the wheel for postseason testing later this month and start working with the team as we prepare for the 2025 season together.”
HMD president Mike Maurini welcomed the arrival of the 22-year-old.
“It is great to finally announce Tommy as part of the HMD Motorsports program,” he said.
“We are excited to have him aboard, and he is ready to work.
“I had the opportunity to work with his management team over the past few months and with Tommy directly in Nashville, and they are all a great group of people.
“They will be a welcomed addition to HMD Motorsports.”
Smith’s season gets underway on the streets of St Petersburg on March 3.