GWS co-captain Phil Davis will be a Giant until at least the end of the 2021 season, after signing a three-year contract extension on Wednesday.

Davis has been with the Giants since their inception into the competition in 2012, and has been a captain in all seven seasons, including the club's 2018 campaign.

103 of his 121 career games have come for GWS, after he spent the first two seasons of his career at Adelaide.

“It’s an exciting time for me and also a great time to be part of the footy club,” Davis told gwsgiants.com.au following the announcement.

“It was a very easy decision, I really didn’t have to put too much thought into it and it was a pretty quick process in the end.

“It’s been a great journey so far and hopefully there’s a fair few years left. I’m looking forward to the next four years if you include this year.”

GWS List Manager Jason McCartney was thrilled with Davis' commitment to the club, and says it follows on from the re-signing of Toby Greene last week.

“We had no doubt Phil would extend his contract but it’s always a great day when you sign your co-captain up,” McCartney said.

“Phil is an exemplary leader of this club and we wouldn’t be in the position we are today without him.

“On-field he’s coming off two really consistent seasons where he’s been able to show the competition why we’ve always regarded him as one of the best defenders in the game.”

GWS have also announced the signing of defender Isaac Cumming until at least the end of the 2020 season.

Cumming is yet to make his AFL debut, but was selected with the 20th pick in the 2016 AFL Draft.