DAYS after producing one of the moments of the first week of the finals, Sydney has rewarded defender Robbie Fox with a new two-year deal after a career-best patch of form.

With the Swans locking away co-captain Callum Mills for six more years on Tuesday night, AFL.com.au understands Fox has now signed an extension until the end of 2024 after the club finalised a new deal with his management, Mac's Sports.

Fox has been forced to earn every game and every contract since being plucked out of the VFL as a 23-year-old via pick No.34 in the 2017 Rookie Draft, only signing one-year deals across his first six seasons at the SCG.

It was only a matter of months ago that the qualified teacher was putting plans in place for next year if he didn't secure another contract, after starting the season in the reserves before injuring his hamstring in the VFL.

But since returning to John Longmire's side in round 11, Fox has played 12 games to form a vital cog in a formidable defence that includes former rookies Dane Rampe, Jake Lloyd and former No.1 pick Paddy McCartin, who was added to Sydney's rookie list in January via the pre-season supplemental selection period.

DONE DEAL Swans co-captain inks long-term contract extension

In the space of five weeks between rounds 15 and 19, the 29-year-old Fox bettered his personal best disposal haul four times, collecting 25 against Adelaide in round 19 to entrench himself inside Sydney's best 22.

Fox was lauded for his multiple defensive efforts in the same play against Melbourne in last Friday night's qualifying final win at the MCG, where he sprinted from the centre of the ground to deep inside defensive 50 to prevent Jake Melksham and then Charlie Spargo from kicking a goal.

The Burnie Dockers product was delisted by the Swans at the end of 2020 before a new AFL rule was introduced that allowed clubs to transfer players from the primary list to the rookie list.

Fox originally moved from Tasmania to Melbourne to study teaching at La Trobe University before joining Aberfeldie in the Essendon District Football League, where he caught the eye of Coburg.

Two years later, veteran Sydney talent spotter Kinnear Beatson pulled the trigger on the mature-age prospect, who had previously represented his state in basketball before shifting his attention to football.

Now Fox has turned into another one of Sydney's many rookie success stories.