20-year-old former Middlesbrough left-back Ashley Corker returns to the professional ranks after a spell playing in non-league football.
He impressed Town manager Gary Johnson in a recent trial spell, Johnson telling the official club website: "We have been looking for a full back who is an athlete, and full of energy and Ashley fits the bill."
Corker is joined at Sixfields by Chelsea goalkeeper Sam Walker. The towering 19-year-old, who impressed on loan at Barnet towards the end of last season, will spend the whole season with Northampton.
"He comes highly recommended by Chelsea," said Johnson.