The Reds defender has used his Twitter page to offer his support for the man who is set to play behind him next season following Edwin van der Sar's retirement.
The 20 year-old Spaniard's style has already caught the eye of the United centre-back.
Ferdinand tweeted today, "David de Gea welcome bro! Another quality young player signed, Manchester United have had a nice bit of movement in this transfer window.
"De Gea has got nice feet too. I love that in a keeper...sweeper."
Striker Michael Owen added: "I'm sure he will be a massive success."