It is the Salford-born midfielder's first move away from Old Trafford and comes after his development was slowed by injury problems over the past two seasons, despite interest from Borussia Dortmund as far back as April 2025.
Fitzgerald made 16 appearances in Premier League 2 last term as Manchester United's Under-21s reached the final of that competition, and has previously won both the Under-18 Premier League and Under-18 Premier League Cup with the club's academy.
He was handed a taste of first-team involvement under Ruud van Nistelrooy during the Dutchman's brief spell as interim manager following Erik ten Hag's departure, named among the substitutes for a 5-2 Carabao Cup win over Leicester City, a 1-1 Premier League draw with Chelsea and a 2-0 Europa League victory over PAOK Salonika, though he is yet to make his senior debut.
Fitzgerald has drawn comparisons to Barcelona and Spain great Sergio Busquets for his reading of the game, and can play in central defence as well as in midfield. Rotherham's connection to Old Trafford runs deep:
Dan Gore was named the Millers' Player of the Year last season during his own loan from United, and it was a phone call from Gore that helped persuade Fitzgerald to make the move to South Yorkshire.
Fitzgerald becomes the League Two club's 13th new arrival of the summer and their third loan signing, following goalkeeper Julian Eyestone from Brentford and wing-back Jill Buyabu from Sheffield United. New head coach Alex Bruce is still working the phones ahead of Tuesday's deadline, having missed out on Blackpool striker Kylian Kouassi, who is instead set to join Colchester.
Rotherham head into the new week on the back of their first win of the season, a 2-1 victory over Chesterfield — Bruce's first success since taking over at AESSEAL New York Stadium. Speaking after that win, the head coach said there were "a few irons in the fire" as he continued to assess further additions before the window shuts.
Fitzgerald is not the only United academy graduate to have joined the Millers in recent seasons. Alongside Gore, winger Gabriele Biancheri also spent time on loan at Rotherham, though injuries prevented him from making the same impact.