The signing has made national headlines because Smith was one of three former Foxes who were filmed, on Leicester's post-season tour of Thailand, taking part in a racist sex video.
Saying he was 'deeply ashamed' of the incident, Smith told BBC Radio Northampton that he was keen to get involved in his new club's anti-racism initiatives.
"I'm just pleased the manager here has given me a second chance. He's put his faith in me and it's down to me to repay that in the training ground and on the pitch if he selects me."
The 22-year-old certainly has a chance to become a first-team regular at Sixfields after the summer departure of Matt Duke.