Willey, 32, left Wantage Road for Headingley ahead of the 2016 season, citing his desire to play with “some of the best players in the country” and signed a contract extension in 2019.
But he said that he has always hoped to return at some stage in his career and has signed a four-year contract until the end of the 2026 season.
“The best journey takes you home.” Willey said. “Wantage Road is home. I grew up playing on the outfield, behind the stands and in the groundsman’s shed.
“When I think back to my first introduction to cricket, I think of Northants. Northants supported and nurtured me in my younger years and gave me the opportunities to achieve my childhood dreams.
“During the seven years I’ve been away, I have continued to watch the club closely and found myself celebrating their successes. I always hoped at some stage in my career I would find my way back and I’m excited that the time is now.
“My love and passion for Northamptonshire has always been there and I hope I can give the club more than just my runs and wickets.
“I still have great ambitions in the game, to play at the highest level, to win trophies but also to give back to the club that has given me so much.”
His return represents a major coup for Northants at a time when several members of their first-team squad are approaching the end of their respective contracts and weighing up their futures.
Ricardo Vasconcelos, the club’s red-ball captain, is under contract until the end of the 2024 season but a clause in his deal means he can leave at the end of this season. Somerset are favourites to sign him with wicketkeeper-batters Steven Davies and Tom Banton both approaching the end of their contracts but several counties are interested.
T20 captain Josh Cobb is among the other Northants players out of contract at the end of this season, along with Emilio Gay, Luke Procter and Ben Sanderson.
Ray Payne, the club’s chief executive, said Willey’s signing was “a significant move that makes our ambitions for the professional squad really clear”.
“We’ve already seen what he’s able to do for the Steelbacks,” Payne said, “and the international experience David has gained in white-ball cricket further strengthens our squad and really supports our goals of bringing more trophies at Wantage Road.”
Darren Gough, Yorkshire’s interim director of cricket, said: “The club was keen to keep Dave at Headingley, but unfortunately were unable to match Northants’ offer.
“We proactively engaged with Dave on his return from the IPL at the end of May, but were not able to make an offer until our new Board were in place. Since our first cricket strategy meeting with the new Board, we have begun negotiations on a number of contracts with players and look forward to making some exciting announcements in the coming weeks.
“Everyone at Yorkshire would like to thank Dave for his time at the club and wish him all the very best for the future.”
Matt Roller is an assistant editor at ESPNcricinfo. @mroller98