"Chris is here to give us the option of an extra defender through a busy period," Cobblers boss Aidy Boothroyd told the official club website.
"With the loan window closing and injuries to John Johnson and David Artell, I felt we needed another defender in the squad to see us through a hectic run of games."
22-year-old Smith had an unusual route into league football, signing for Swindon in February of this year after beating off 5,000 other applicants in a series of trials to win a contract with Swindon.
