The 22-year-old was one-year into a multi-year deal with the Campbellfield squad, and no replacement has yet been named.
However, it is understood that Declan Fraser, who had been unsuccessful in landing a drive in the Championship despite winning the Dunlop Super2 Series, will take over Kostecki's seat in one of Tickford's Gen3 Ford Mustangs.
It is thought that the premature split between the two parties was triggered by a physical altercation between Kostecki and Team 18's Scott Pye at the Supercars Gala Awards which took place on the evening after the 2022 season-ending Valo Adelaide 500.
Nevertheless, the parting of ways is said to be a mutual decision, although it was announced via a particularly brief statement from the team and no individual was quoted.
Entitled ‘Tickford Racing and Jake Kostecki part ways', said statement read, in its entirety:
“Tickford Racing and driver Jake Kostecki have decided to part ways by mutual agreement and will not continue with their partnership in the 2023 Supercars Championship season.
“Tickford wishes Jake well in his future endeavours.
“The team will make further comment on its 2023 driver line up in due course.”
He became a regular in the top tier by way of Matt Stone Racing's ‘SuperLite' programme in 2020 when he shared one of its ZB Commodores with Zane Goddard, before both got a ride of their own at the Yatala-based squad in 2021.
The West Australian finished 2022 in 22nd position in the drivers' standings, one spot ahead of the driver with whom he shared the second Tickford garage in Thomas Randle, having scored a season-best race result of eighth in the latter encounter at Darwin's Hidden Valley.
Kostecki's exit makes for an unexpected change to Tickford's full-time driver quartet from 2022 into 2023, with Cam Waters, James Courtney, and Randle all continuing.
Waters finished second in last year's drivers' championship, with he and Courtney giving its #5/#6 entries a collective third place in the teams' championship.