The 27-year-old had joined Berko in September 2020 from Vanarama National League South side Braintree Town.
He had been with the Iron since October 2019 after arriving from then-Isthmian League North outfit Cambridge City.
Kirkpatrick has also had previous spells Bedford Town, Biggleswade Town and Hitchin Town, where he spent almost five years and made over 200 appearances, plus turning out for Kempston Rovers and Langford.
Tweeting about his move, Kirkpatrick wrote: “Joining a very strong @afcdunstable side, excited for next season.”
There were more confirmed signings for Steve Heath’s side last week too, with former Luton youngster Christian Tavernier agreeing to stay.
The club tweeted: “Christian joined us in 2017 from Arlesey Town.
"Another loyal player who now enters his fifth season as an OD's player.
"Having suffered a relatively serious eye injury whilst playing, Christian recovered well and played an important role in the team last season but unfortunately missed the climax to it with a groin injury.
"We look forward to seeing CT back in action in the coming weeks.”
Also staying at Creasy Park was Ben Farrell, as the club commented: “The experienced midfielder joins for his second season.
"Previously with AFC Rushden & Diamonds, Ben is a popular member of the squad and has experience of National League football.”