Valdes began training with United earlier in the season and at first it appeared it was just so the 32-year-old could regain fitness, with rumours linking him with a move to Liverpool.
But as time went on and the longer Valdes stayed at the club, it appeared likely he would be offered a contract with Anders Lindegaard set to leave the club.
The former Barcelona man officially joined United on Thursday night and van Gaal explained why he’d taken up the chance to sign him.
“When you invite Victor Valdes to have his rehabilitation here at Manchester united, you do that for him, but also for yourself,” said Van Gaal.
“I had the chance to see him and his behaviour in rehabilitation but also if his quality was still the same. He has confirmed both and that is very important for me and also for him because when I am satisfied then mostly the players are satisfied.”
Now that Van Gaal appears to have a number two he trusts, it wouldn’t be a surprise to see Valdes get his debut against Cambridge United in the FA Cup.