Valdes has been training at United since October as part of his bid to recover from a knee injury he suffered in March.
The Spaniard has now regained full fitness and United confirmed he had signed a deal with the 20-time English champions.
"Manchester United is delighted to announce that Victor Valdes has signed an 18-month contract with the option to extend for a further year," a statement from the club read.
Source : PA
Source: PA