Now aged 32, the striker netted 11 league goals for the Cobblers between 2003 and 2005 before productive spells at Barnsley, Port Vale and Chesterfield.
Manager Chris Wilder moved quickly to snap the player up after Northampton’s League Two status was confirmed and will look to Richards to be his main goal threat this season in an area where Town struggled for large parts of a dismal campaign.
The bookmakers offer a best-price of 25/1 that he tops the divisional scoring charts. Another player returning to a former club is the favourite with Ryan Lowe expected to have a fruitful campaign back at Bury.