Toure’s 70th-minute placed finish from outside the area came after exchanges of passes with Nigel de Jong and Sergio Aguero, and gave the visitors a lead in a match where there had been chances for both sides.
In the final stages Toure and Aguero spurned some gilt-edged chances to settle the nerves, but an 89th-minute counter-attack ended with the Ivorian beating Tim Krul at his near post to wrap up the match.
Manchester United later won 2-0 at home to Swansea to stay in touch with their city rivals, but the men in blue have negotiated perhaps the trickiest remaining stumbling block to a title triumph.
City and Newcastle came into the game as the division’s two in-form sides, both knowing that their destiny in the Premier League was in their own hands.
Victories in their final two league matches would all but secure visitors City their first title since 1968, while for Newcastle two wins would guarantee a top-four finish.
Both sides named unchanged sides after last week’s successes, but with so much at stake the game took a while to ignite.
The away side settled first, with David Silva testing Tim Krul with a low shot across goal.
The attacking options Manchester City boasted began to tell, with Toure a commanding presence from deep. His midfield partner Gareth Barry played in Silva who found Aguero with a crisp diagonal pass, only for Krul to again make the save.
Newcastle were forced on to the back foot, but they stuck to their task, hoping to hit on the counter-attack.
Their first opportunity came after half an hour when Hatem Ben Arfa wriggled down the touchline and teed up Demba Ba for a decent drive from 25 yards out, but their best chance of the half came five minutes later.
Jonas Gutierrez finally found some space on the left and picked out Ba, whose goalbound effort was superbly blocked by Gael Clichy. The ricochet fell to Ben Arfa, but a quiet first half did not stop Joe Hart being alert enough to save.
The game opening up, and with a draw not ideal for either side, opportunities began to present themselves for both sides in a needly first half, which saw referee Howard Webb make five bookings.
But the best of the lot fell to Gareth Barry, who twice had shots following Silva’s cutback blocked, the second on the line by the composed Davide Santon.
A goal had looked inevitable, but the intensity of the match dipped as the second half resumed.
City, who had more of the possession throughout, had their chances – Tevez snatched at a shot when he had more time than he realised, flipping the ball high and wide when he ought to have hit the target.
At the other end Ben Arfa blazed a shot beyond the near post when he had jinked his way into a good position.
De Jong replaced Nasri and Tevez was withdrawn for Edin Dzeko as Roberto Mancini looked to shake the game up – and the Dutch midfielder had a hand in the goal worthy of settling a title race.
Toure’s side-footed effort followed an impressive exchange of passes on the edge of the Newcastle area, and without powering his shot he still had the beating of Krul from more than 20 yards out.
Newcastle remained a danger, however, which made one-on-one misses from Aguero with a quarter of an hour to play, and then again from Toure with seven minutes left, unnerving for the league leaders.
The quiet Papiss Cisse, marshalled expertly by Vincent Kompany all match, flashed a header wide, while substitute Shola Ameobi had a shout for a handball rejected after his shot was blocked by Micah Richards.
But City pounced on the break, with Aguero and Clichy teeing up Toure to finish with composure on his left foot.
Newcastle missed an opportunity to cement a Champions League spot, and end the day in fifth position.
The title race has not been categorically settled, but Manchester City will be preparing for a party at their final game of the season at home to QPR.