The 19-year-old key forward, who has been on the verge of selection for several weeks, will play against Hawthorn at Norwood Oval on Sunday.
Cadman has been called up after his strong form at VFL level, as the Giants seek to snap a three-match losing streak.
"We know it's been a waiting game for Aaron, who has been incredibly close to selection multiple times," Kingsley said.
"We've been really impressed with what we've seen from Aaron over the pre-season and opening rounds of the VFL, and have full confidence he'll come in and play his role for the side on Sunday."
GWS gave up two first-round draft picks as part of the so-called "mega trade" last October in order to secure the top selection, with Cadman at the forefront of their plans.
The Greater Western Victoria Rebels product - from Darley, about an hour outside Melbourne - had previously made it known he would have no issues moving to Sydney.
Cadman has since had an immediate impact at the Giants, impressing coaches and teammates alike.
"He's come into our club with a great attitude," Kingsley said.
"He's worked hard and is so eager to learn and these are all traits that will set him up for a long career at AFL level.
"It's a really exciting time for him and we can't to have him run out as part of our side to take on the Hawks."
GWS beat Adelaide in round one but have since suffered successive defeats at the hands of West Coast, Carlton and Essendon.
They take on a last-placed Hawthorn side that is reeling from an 82-point hiding dished out by Geelong on Monday.
The Hawks will also unveil a debutant at Norwood Oval, calling up speedy utility Seamus Mitchell.
The 20-year-old was a second-round draft pick (No.29 overall) in 2020 and has made the most of an injury-free run this season after numerous setbacks.
"He absolutely deserves this opportunity," Hawks football boss Rob McCartney said.
"Gifted with genuine speed, Seamus has shown a great ability to play a rebounding defender role and be a real weapon for his side in generating offensive drive."
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