The deal will see the Cats trade draft pick 21 to St Kilda in return for Stanley and draft pick 60.
Recruited from West Adelaide, Stanley was taken at pick 47 in the 2008 national draft.
Stanley debuted in 2010 and went on to play 58 games over his six years at St Kilda.
At 200cm, the 23-year-old athletic forward also has the ability to play a role in the ruck.
A previous grand final sprint winner, Stanley’s pace and versatility has the club looking forward to what he can bring to the team.
Geelong football manager Neil Balme said the club was very pleased to secure Stanley’s services.
“We are very happy Rhys will be joining the club, he is a valuable player with great potential.
“Rhys’ ability to play a number of roles has us excited about his future prospects.”
Stanley is the second new face at the Cats after Mitch Clark officially joined the club earlier today.
