He said: "Although I can't be at the Vale often enough, my investment is just to say that my heart is still there and I'm a huge supporter.
"I'm really excited about what we may be able to do with the club in the future."
Vale chairman Bill Bratt added: "We will be playing even more Robbie music than ever at the important home game against Scunthorpe.
"This news will raise Vale's profile around the world and help us to be seen as a more fashionable club. I think there are few more Vale fans who believe in angels."