The Argentine, signed for a reported 45 million euros from Atletico Madrid, vowed at the time he would "fight to the death" to bring the glory days back to City and with 60 seconds of injury time left at the Etihad and the score 2-2 he delivered.
Speeding into the area he was as cool as a cucumber to smash the ball past QPR goalkeeper Paddy Kenny before celebrating by whipping off his blue shirt and waving it above his head and then being buried under a pile of his team mates.
It was his 23rd league goal of an impressive first season in English football and by far the most priceless.
"I'm really really happy," Aguero, husband to one of Diego Maradona's daughters, said on the pitch as ecstatic fans chanted his name inside the stadium following the 3-2 win that nicked City the title on goal difference from Manchester United.
"We can hardly believe it ourselves. We thought the Premier league had gone but thank God it worked out for us.
"We scored twice in the final five minutes. It's absolutely unbelievable.
"It was getting very complicated and difficult for us but we made the most of that five minutes [of stoppage time]."
With former crowd favourite and fellow Argentine Carlos Tevez having fallen out of favour with the club's fans following his public spat with coach Roberto Mancini after refusing to warm up in a Champions League tie in September, Aguero has become the new darling of the Etihad faithful.
"They've treated me very well from the moment I arrived," he said. "Let's hope this is the first of many titles.
"My personal objective is to keep improving as a player and win more trophies. This has given me even more confidence."
Pablo Zabaleta, Aguero's countryman who gave City a halftime lead before things got sticky in the second half, said the striker's impact had been crucial this season.
"He makes all the difference," he said. "He is an unbelievable player and he always appears in the best moments."
