An injury-hit GWS have consolidated their spot in the AFL top-four and ended Adelaide's season by 14 points in Canberra.
The Giants' 13th victory of the season - and fifth in a row - was hard-fought as the Crows' slim finals hopes were on the line, but Leon Cameron's side held on to win 15.16 (106) to 13.14 (92) on Saturday.
But GWS's cursed injury run has continued as veteran defender Heath Shaw (knee), All-Australian midfielder Josh Kelly (concussion) and Sam Reid (hamstring) all failed to see out the match.
Kelly was knocked out after a heavy tackle from Crows' skipper Taylor Walker in the third quarter that is certain to draw attention from the match review officer.
But Shaw's injury appears to be the worst of the lot, with the Giants fearing a suspected a PCL which would rule him out for up to six weeks.
Shaw went down midway through the final quarter and was taken from Manuka Oval on a medicab, but he looks to have avoided the dreaded ACL.
Despite being down to one fit player on the bench, GWS were able to hold out a determined Crows team, desperate to avoid missing the top-eight following a grand final appearance last year.
Nothing separated the sides in the first half, but a Jacob Hopper goal just before three-quarter time saw the Giants take an 11-point lead into the final change.
After a tense final term, Hopper again popped up to kick the sealer with five minutes to go, taking the Giants to a 21-point lead.
Former No.1 draft pick Lachie Whitfield (30 possessions) and co-captain Callan Ward were shining lights for the Giants, while Jeremy Cameron, Harry Himmelberg, Aiden Bonar, Stephen Coniglio and Hopper booted two goals each.
Giants coach Leon Cameron called it an "outstanding" win considering their growing injury toll.
"Our first half was a little bit off and Adelaide were playing some great footy," Cameron said.
"We were lucky they didn't punish us a bit more ... going in four points down at half-time probably didn't tell the full tale."
A major positive for the Crows was the performance of Brodie Smith, who collected 29 touches in his second game back from ACL surgery, while spearhead Josh Jenkins finished with three goals.
"We ran into a really good team tonight, who play a strong brand of footy but in some of the key moments we lost those and the Giants were able to capitalise," Adelaide coach Don Pyke said.
"We've got a couple of games to go so really important we focus on those games and get ourselves hopefully a couple of wins."