The former Tyrone, Louth, and Derry boss will be working alongside Declan Kelly.
Offaly GAA has announced Mickey Harte will jointly manage the Offaly Senior footballers with Declan Kelly, pending approval at the next meeting of the county board.
Once confirmed, Harte will commence a three year term with the Faithful County.
The recently departed Derry boss has previously won three All Ireland titles with Tyrone in 2003, 2005, and 2008.
Harte was chosen by the county's Football Management Review Committee and subsequently approved by Offaly's GAA Management Committee.
He says: "I am really looking forward to working with Declan and the players over the next three years. I am very aware of the history and tradition of Offaly football and believe that there is huge potential within the county. I am very excited to work with Declan and the players to get the best out of the footballers in both the League and Championship in 2025. I would like to thank Michael Duignan for his professionalism and honesty during our meetings".
Offaly head into 2025 off the back of a disappointing season.
Declan Kelly's first campaign over the Senior footballers yielded little in the way of positive results.
Relegation from Division Three of the league was narrowly avoided.
That was followed by a good win over eventual Tailteann Cup finalists Laois in the Leinster Championship.
Offaly were knocked out by Dublin next time out.
The Tailteann Cup campaign will be remembered as the lowest point of 2024 with a heavy home loss to London signalling the end of any genuine hopes of making an impact on the competition.
Kelly meanwhile has welcomed the move:
"This is great news for Offaly football and Offaly GAA in general. I look forward to working closely with Mickey. He has had huge success over the years and we hope to emulate that in the not-too-distant future".