The 23-year-old Inverness defender will join the Dons on a three-year deal when the transfer window opens in June.
Shinnie, an Aberdonian, signed for Caley in 2009 and has made over 140 appearances for the Highlanders.
Last season the former Scotland Under-21 international was selected for the PFA Scotland Team of the Year and according to a statement on Aberdeen's website, "chose to join Aberdeen despite offers from English Championship clubs."
It is thought that the Dons will now attempt to negotiate a deal with Inverness that would bring Shinnie to Pittodrie before the January transfer window closes, to bolster the club's assault on the league title.
Source: PA Sport