The winger signed for the League One club on Thursday for what they described as a “sizeable” undisclosed fee, penning a long-term contract and handed the No10 shirt vacated by Abraham Odoh’s recent departure for Salford.

Williams is one of several youngsters - including 15-year-old sensation JJ Gabriel - to feature during Man Utd’s current pre-season tour across Europe.

The 20-year-old scored the final goal in a 5-0 rout of Norwegian side Rosenborg in Trondheim last month, also featuring against Wrexham and Atletico Madrid before being omitted for the meetings with Paris Saint-Germain and Leeds as a number of Michael Carrick’s senior players returned following post-World Cup breaks.

Williams is a graduate of the Manchester United academy, having first joined the club from Rochdale in 2019.

He spent the entirety of last season on loan in the Scottish Premiership with Falkirk, scoring one goal and registering three assists in 24 appearances across all competitions as the Bairns secured a top-half finish in their first campaign back in the top-flight.

Williams already has previous EFL experience from his time on loan at League Two side Cheltenham during the second half of the 2024/25 season, when he scored twice and had two assists in 17 appearances.

He never made a competitive senior appearance for Manchester United, though also played and scored during pre-season last year and was a regular at youth level for the Under-18s and later the U21s.

Williams will hope to make a quick Peterborough debut on Saturday, when Luke Williams’ side open their League One campaign away to Bradford at Valley Parade following a Carabao Cup first-round win over Bristol Rovers.

Williams told Posh+ after his move was confirmed: “The identity of this club is clear, they like to work with younger players and when I heard of the interest, it was a move that I wanted to make.

On target: Ethan Williams celebrates after scoring for Manchester United in their pre-season friendly against Rosenborg

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“I have been out on loan at a couple of clubs, have gained a lot of experience of men's football and felt it was the right time to leave United and sign for Peterborough.

“I have enjoyed my time at United and it's always tough to leave a place like that, but there comes a time in your career where you have to make tough decisions to develop yourself and Peterborough is renowned for helping younger players.”

Peterborough said they had “fought off interest in Williams from a host of other clubs”, with manager Luke Williams adding: “Ethan is a player that will give us another option in the wide areas, he is quick, direct and will be a threat and I am looking forward to working with him.

“He has already got first team experience at a few clubs and joins us after being away with Manchester United on their pre-season tour, so he is fit and ready to go.”