The 19-year-old impressed in a trial game at Sixfields earlier in the summer and during pre-season and boss Stuart Gray has rewarded him with a contract.
Howe, who was released by Milton Keynes at the end of last season, can play in midfield or at full-back
Gray told the club's website: "Joe brings flexibility and potential. He adds more depth by being able to play in more than one position."
BBC