The Hawks veteran had been spending time away from the club for the past fortnight following the passing of his father Ray Gunston - a popular football administrator.
Given the circumstances, Hawthorn provided Gunston with as much time away as was required, but the three-time premiership player is now ready to return.
Meanwhile, Changkuoth Jiath has been ruled out through injury for the weekend with some minor bone bruising in his knee.
Jiath expressed soreness in his knee after his side's Round 18 win over West Coast last weekend, and subsequent scans have revealed that he will be out of action for at least once week.
"It’s really unfortunate that Changkuoth has suffered small hiccup after some strong performances in recent weeks,” McCartney said in a club statement on Thursday.
"Our medical team has indicated his knee is structurally sound, opting to take conservative approach given his age profile.
"We are hopeful of having CJ on the park for our Round 19 match against St Kilda."
Hawthorn coach Sam Mitchell is unlikely to make any other unforced changes, but is reportedly considering recalling wingman Tom Phillips and onballer Liam Shiels, who have both excelled for Box Hill recently.
Saturday's fixture will see the Hawks contest for premiership points for the first time at Bellerive Oval in Hobart.