The 20-year-old comes with considerable pedigree having joined the Red Devils from Chelsea's academy four years ago.
He played Europa League football in 2019-20, and spent last season on loan at Salford City, making 31 appearances in League Two's meanest defence.
Coach Grant McCann had said the Tigers were surprised to learn that under the terms of their transfer embargo they were unable to add to their then-five transfer window signings without any players leaving permanently. The Championship club had been under the impression the loan departures of Callum Jones and Jordan Flores would suffice.
But with talks ongoing about the issue, the fact this transfer has been completed is a positive sign.
Hull are only allowed to sign players on loans or free transfer because they borrowed money from the Football League to help them through the Covid-19 pandemic. The rules state that they can only add players up to a squad limit of 25 senior footballers, and that even though they will be playing for Morecambe and Northampton Town respectively next season, Jones and Flores are part of that number.
McCann still hopes to sign two more midfield players, with former England international Tom Huddlestone a possibility after playing and training with them in pre-season, but he is delighted with the latest arrival.
“Everyone knows we were in the market for a right-sided centre-half and we’ve waited patiently for Di’Shon," he said.
“The fact he’s been in the Manchester United first team the past few weeks and been part of their pre-season plans shows how highly they think of him.
“From speaking to Michael Carrick, and one or two other people at Man United and Salford, I feel it’s a positive progression for the lad.
“He’s confident and got lots of qualities; he’s quick, good at handling the ball, aggressive in the way he plays, wants to play on the front foot and likes to drive forward.
“We feel we’ve got a really good player on our hands and we’re looking forward to working with him.”