The transfer deadline day signing's first-half stunner gave Simon Davey's men a second win in succession, to lift the Tykes three places and out of the relegation order.
The Sky television cameras rolled into the Potteries for a clash between a City side who had not won in their last four home outings and a side flirting dangerously with the drop.
And if that billing didn't have audiences channel-hopping in their droves, the first 45 minutes from the Britannia Stadium certainly did.
Clear-cut chances were scarce, and even when they did arrive they were duly wasted, Jonathan Fortune the most culpable party in the 15th minute.
The defender somehow caught nothing but fresh air after finding himself unmarked in the Barnsley box, when Liam Lawrence drove in a teasing centre from the left.
A few party-pieces from City schemer Lee Hendrie briefly punctuated the tedium, but not even a samba-style master-class could lift the Potters contingent on the 43rd minute.
The on-loan midfielder was turning it on for the cameras with a succession of flicks, before Ferenczi spoilt the show.
The Hungary international pounced when Fortune made a real hash of a routine clearance to leave the striker closing in on Steve Simonsen.
The in-form striker made no mistake with his finish, curling a shot superbly round the City keeper to give the visitors a somewhat undeserved half-time lead.
Ferenczi had another go, but steered a header around the target after rising well to get on Brian Howard's centre, but it was the hosts who looked the more likely to score.
A bombardment of late pressure should have paid dividends, but a lack of composure in front of goal left the Potters' play-off hopes in tatters.
Adam Rooney and Carl Hoefkens both squandered late chances, while Grant McCann was busy keeping Barnsley's hopes of Championship survival alive.
The midfielder was fortuitously placed to keep out Mamady Sidibe's towering header to seemingly justify those "we are staying up" chants echoing from the away end at full-time.