The 38-year-old's primary responsibility will be working with the Cobblers' keepers but he has also been registered as a player in case he is required by new manager Rob Page.
"Coaching is something I always wanted to do when my playing career ended," Kenny told BBC Radio Northampton.
"I've seen it more over the last few years as I've got older and when I'm training I tend to have more input with the younger lads.