The Sweden striker hit his eighth goal in 13 Premier League appearances as the Magpies came from a goal down to make it five wins in a row and stay in third place.
A high-tempo match in west London also featured a collector’s item in the shape of a missed penalty by Ivan Toney.
The England striker also scored from the spot and had a goal disallowed in an eventful first half.
Toney thought he had fired Brentford ahead in the seventh minute after Nick Pope clawed out a header from Pontus Jansson.
Toney snaffled the rebound but a VAR check showed he was just offside when Jansson headed the ball.
The penalty saga began when Kevin Schade superbly brought down a high ball before racing past Dan Burn and into the area, where he was unceremoniously halted by Sven Botman.
But Toney’s effort was uncharacteristically weak and Pope saved low to his left to join Adam Davies of Barnsley in an exclusive club of the only goalkeepers to keep out a penalty from the striker, when he was at Peterborough in 2018.
Four-and-a-half years and 24 successful penalties later – including 22 out of 22 for Brentford – Toney’s run had finally come to an end.
However, the 27-year-old is nothing if not confident about his ability from the spot, and normal service was resumed in first-half stoppage time after Isak caught Rico Henry.
Referee Chris Kavanagh was instructed by the VAR to check the pitchside monitor and, inevitably, he awarded another penalty.
Take two for Toney, and he dispatched it, to Pope’s left again but this time high enough to beat his dive.
Newcastle had been below-par in the first half but the introduction of Callum Wilson and Anthony Gordon pepped them up, and they equalised in the 54th minute when Kieran Trippier found Joelinton inside the box.
Rarity: Toney had first missed a penalty before scoring
/ REUTERSThe Brazilian evaded a challenge from Ben Mee before drilling a low cross which was diverted in via the heel of Brentford goalkeeper David Raya.
Six minutes later Wilson, unfortunate not to start after his double at West Ham in midweek, squared for Isak to lash a superb effort from the edge of the box into the top corner.
Raya made a fine block to deny Isak a second before Wilson prodded the ball home from a corner, only for another VAR review to chalk it off for handball after the striker controlled the ball with the top of his arm.
Pope kept out Ethan Pinnock’s late header and Toney headed over in stoppage time as Brentford slipped to only a second home defeat of the season.
