The experienced defender, who also had notable spells at Bristol City and Swindon, impressed during pre-season and will have the option to extend his contract for a further 12 months.
The 31-year-old becomes Aidy Boothroyd's sixth summer signing and the Cobblers boss is happy to have a player of his experience at the club.
"He is exactly what we need. He has a presence, he is good size but he is a footballing full-back," said the former Watford boss.
"He knows all about League 2 and what is required. He is a promotion winner in the past and he is a good professional to be coming in to our dressing room.
"He is different to what we have and his arrival is a boost for us."