The visitors pulled one back from the spot in the 75th minute, but Oscar Bobb was on hand soon after to restore our three goal lead with a clever close-range finish.
An impressive performance from the Young Blues, with last week’s defeat, which ended an incredible 20-game unbeaten run, a distant memory.
With Liverpool getting the better of Sunderland earlier on, City knew they had to be quick out of the traps to put the pressure back on the top two.
And they almost took the lead just after the five-minute mark when Taj Sodje broke down the left before squaring for Kian Breckin, but the midfielder could not divert his first-time effort from the edge of the box on target.
Ten minutes later it was Robertson’s turn to go close, picking up a loose ball and darting his way through a couple of Boro challenges before poking a low effort inches wide of the far post.
Middlesbrough held firm in three solid, disciplined banks despite City enjoying the majority of the play, but Carlos Borges nonetheless almost capitalised on a moment of indecision on the half-way line, racing through before forcing a smart save from Max Metcalfe.
But the visitors showed they too possessed an attacking threat, with Andrew Nelson heading marginally over the bar from an inviting right-wing cross.
That chance sprung Carlos Vicens’ youngsters back into life however, and they found the breakthrough their play deserved just before the half hour.
A quick turnover on the City right released the hot-heeled Borges in behind and, on the rebound, he calmly placed the ball into an empty net.
And we almost added a second five minutes later when Robertson once again danced his way through several challenges before stinging the palms of Max Metcalfe at the near post.
But the midfielder was not to be denied a second time, smashing a ferocious effort into the top corner after being fed through by an incisive Breckin pass with half-time approaching.
A devastating ten minutes was then capped off by Borges, who smashed home his second of the game on the angle after impressive combination play from Robertson and Sodje.
City continued to enjoy the lion’s share of the possession in the second half but the game began to get bogged down in the centre, where both sides were battling relentlessly for the upper hand.
Just after the hour, the visitors had two chances in quick succession, the first of which saw an overhit cross from the right clip the top of the bar, before Josh McNamara expertly denied Calum Kavanagh from close-range to preserve the clean sheet.
But Middlesbrough eventually got their goal, with substitute Josh Coburn sending McNamara the wrong way from the spot with 15 minutes to play.
Undeterred, City pressed forward to make sure they had the final say, and they got their just rewards when Bobb latched onto a clever through pass, cut in onto his left before reversing a clever effort in at the near post to end the scoring at the CFA.
What it means
While City remain third in the U18 Premier League table, the win means they remain three points behind Liverpool with three games in hand.
Carlos Vicens’ side are six points behind leaders Manchester United, but have played one less match.
How we lined up
Harvey Griffiths, Breckin and Robertson formed the midfield three, with Borges and Bobb providing the width for Sodje at the sharp end.
It’s a quick turnaround for our Young Blues, with a trip to Wolves next on the Premier League U18 calendar in four days’ time.