His decision comes a week after it was confirmed that Chiefs boss Clayton McMillan will take over from Graham Rowntree, who vacated the Munster head coach role last October.
It was earlier in January when RugbyPass exclusively reported that loosehead Milne and hooker Barron were set for moves to Limerick from Dublin and their summer 2025 transfers have now been rubber stamped.
The 29-year-old spent two years at The Stoop between 2014 and 2016, making six appearances before crossing the Irish Sea, where, thanks to his Irish-born mother, he has won 11 Test caps.
The Ireland tighthead, who missed his country’s entire four-match Autumn Nations Series, has featured just twice this season for his province.
Former All Blacks outside back Nehe Milner-Skudder has been named to play for the Highlanders for the first time since signing with the Dunedin franchise last year.
Aaron Smith’s long-awaited return to the green and white jersey will be via the bench when the Turbos take on Northland in Whangarei on Sunday.
The Highlanders have named a settled team to face off against the Crusaders on Sunday, making just one change to their starting side.