The Magpies boss will remain at the club for another two years, they have announced.
The West Ham legend kept the team in the National League last season after struggling in the first half of the campaign.
Now he will turn his attention to next year and looking to improve on their 19th place finish.
A statement read: “Maidenhead United are delighted to announce that Alan Devonshire has agreed an extension to his current contract which will see our manager remain at York Road until at least the end of the 2021/22 season.
“Dev shook hands on the deal with Chairman Peter Griffin at York Road this morning.
“Now in his second spell with the club, Devonshire is looking ahead to only our third ever campaign at National League level next season.”