The 29-year-old has signed a two-year contract at Pittodrie, citing a desire for “a fresh challenge” and more regular playing time.
Cadden made his final Hibs appearance as a substitute in Thursday’s 4-1 Conference League qualifying victory over Malisheva at Easter Road.
He featured 27 times last season, starting 19 matches, and leaves Hibernian after making 166 appearances since joining from Columbus Crew five years ago.
"Chris is a brilliant addition to our group, not just because of what he'll bring on the pitch but because of the character and professionalism he'll add to the dressing room,” said Aberdeen manager Stephen Robinson.
"He has a great engine, always shows a willingness to get forward and support the attack, but he's also matured into a really dependable full-back defensively.
"He was incredibly keen to make this move happen and that tells you a lot about his hunger and his desire to be part of what we're building here."