The long-serving assistant will depart Richmond to take over the Giants.
GWS chief executive David Matthews says Kingsley was the clear-cut choice from a field also featuring Melbourne assistant Adem Yze.
"Adam's vision for the club, our players and our people made him the standout candidate for the job," Matthew said in a statement on Monday.
"Adam has outstanding values that align with the Giants.
"And with 16 years' coaching experience, he is an exceptional tactical coach, a strong, clear communicator, and someone who brings people together."
Kingsley started his assistant coaching career at Port Adelaide in 2007 and also had lengthy stints at St Kilda and the Tigers.
The GWS coaching role was vacated by Leon Cameron in mid-May, with Mark McVeigh taking over as caretaker for the back end of the season.
The Giants finished 16th with just six wins for the year.
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