Tipped by many to have a big future ahead of him, he goes to Old Trafford on a five year deal that has cost the Red Devils something in the region of £16.5million.
United thought they had secured Jones' services last week, only for the transfer to be halted due to an unforeseen snag.
It was claimed Blackburn were holding out for more cash and that Liverpool had jumped in with a £20million offer.
However, 19 year old Jones apparently told Rovers he did not wish to join any other club than United.
"Manchester United is delighted to announce it has signed an agreement with Blackburn Rovers for the transfer of Phil Jones," said a United statement.
"The player passed a medical in Manchester last week and has agreed a five-year contract.
"The deal will be completed once the player returns from international duty."