The 26-year-old has penned a one-year deal and will link up with his team-mates ahead of Tuesday night's friendly with Derby.
He told the club's official website: "I'm over the moon, I'm just glad something could be done, it was in the process for a long time but these football deals tend to go on forever, which in the back of your mind you're thinking is it going to happen?
"I think Vale's style of play suits me and I understand the management, when I joined it was a great place to grow as a player and turn a boy into a man.
"The attraction I got from the supporters as well was fantastic, you have to do the work on the pitch to get respect and that doesn't just come in the first year, I had to keep chipping away in training."
Griffith originally joined Vale in 2008 from Doncaster and spent four years with the club before moving to Leyton Orient.
But he was back at Vale Park in March on loan and he helped Micky Adams' men clinch promotion to League One.