Mellon left the club after their relegation to League Two at the end of the coronavirus-shortened 2019-20 season.
Tranmere have announced Micky Mellon is returning to the club for a second spell as manager.
The Scot, whose tenure starts from Tuesday, arrives back at Prenton Park after leaving Dundee United last week.
He succeeds Keith Hill, who Tranmere sacked earlier this month prior to their League Two play-off semi-final, which they lost to Morecambe.
Mellon was previously Rovers boss from 2016 to 2020 and guided them to back-to-back promotions as they rose from the National League to League One.
He left for Scotland last July after Tranmere were relegated to League Two at the end of the coronavirus-shortened 2019-20 season.
The 49-year-old, who will have Ian Dawes as assistant manager while Andy Parkinson acts as first-team coach, said on Tranmere’s official website: “It is great to be back.
“When I went to Scotland following our demotion from League One, it left a sense of unfinished business and I am pleased to have the opportunity to right that wrong.
“Tranmere is a forward-thinking club with an exciting future, and I wanted to be part of that, so I can’t wait to get started and be reunited with the SWA (Super White Army) once again.”
Chairman Mark Palios said: “It is great to have Micky back at Prenton Park.
“We met up over the weekend to discuss matters and both felt it was a great fit for him to return, so we have moved swiftly to ensure that there is plenty of time to build a squad for the new season.
“In Micky, we have a proven manager who already has a bond with the SWA, having guided us to back-to-back promotions from the National League to League One.
“I am very confident that with his knowledge and experience, and with Ian Dawes and Andy Parkinson alongside him, we will be making a strong push for promotion next season.”