O'Connor, who enjoyed youth spells with the Gunners and Crystal Palace, was named among a lengthy list of players to be leaving the Magpies when their contracts expire at the end of June and is said to be attracting interest from the Saddlers, Blackpool, Fleetwood Town, and Coventry City.
The Croydon-born prospect, who has also spent time on loan with York City and MVV Maastricht in a bid to secure some first-team football, is yet to make much of an impact upon the professional game and has made just eight first-team appearances since turning pro with Arsenal in 2014.
Stefan left the Emirates Stadium club in the summer of 2017 - signing a deal with Premier League rivals Newcastle United - where he would link up with their Under-23s' Premier League 2 side in a bid to force his way into manager Rafa Benitez's first-team plans.
Sadly Stefan would fail to gain any first-team action and will be joining a list of players to depart the North East as Newcastle look to refresh their side ahead of the 2019/20 campaign.
Walsall have already added former Bristol Rovers defender James Clarke to their squad following their relegation to League Two but are still in need of more fresh legs as recently-appointed manager Darrell Clarke begins to prepare his squad for life in the fourth tier of English football.