The 23-year old centre-back has penned a deal which will see him remain with the Terriers until the summer of 2018.
The signing of Smith, who joined Huddersfield from Manchester City in 2012, pleased manager Chris Powell who sees him as an integral part of his squad.
"Tommy has established himself as an important member of our first-team squad and a regular starter both at right-back and also within a back three," Powell told the club's official website.
"He is still a relative novice in terms of professional experience in a tough division, but he has played a lot of Championship games in a short period of time since his debut, which is testament to his ability, fitness and development. Tommy deserves a lot of credit for that."
Huddersfield Town (@htafcdotcom) April 29, 2015