Pep Guardiola's men had to be patient before Sterling claimed his fourth goal of the season shortly before the half hour.
Brighton's defensive work became increasingly last-ditch from that point and Aguero found the goal his endeavours merited in the 65th minute.
Leroy Sane was the most consistent threat during a largely listless opening from the champions and it was no surprise to see him to the fore when they broke through.
Aguero drove City forward on the counter-attack and released the jet-heeled Germany winger, whose cross was slid home by Sterling.
Brighton goalkeeper Mat Ryan denied Sterling and Fernandinho before the break as City moved through the gears.
Kyle Walker sent a shot skidding wide from a similar distance to the one he scored from against Newcastle United last month and Sane misjudged a header from Bernardo Silva's excellent floated cross.
Captain Lewis Dunk produced a sprawling block to deny Aguero in the 58th minute, with Ryan standing firm to repel David Silva's shot in the ensuing scramble.
But there was no stopping City when Aguero barrelled through the midfield and skipped past Dunk's tired challenge. The Argentina striker slid in Sterling, who selflessly supplied a return pass for a tap in.
Fernandinho misjudged a header from a Brighton corner five minutes from time, with the ball striking his arm, but penalty appeals were waved away by referee Lee Mason.
What it means: City in good shape for Anfield showdown
City are arguably yet to hit the heights they scaled during their title-winning campaign, but they head into next weekend's showdown with Liverpool unbeaten in the top flight, with 19 points from a possible 21. They have not won away at Liverpool since 2003. Brighton have acquitted themselves admirably during a tough opening run of fixtures but are winless since beating Manchester United in the second game of the season.
Aguero singing to Guardiola's tune
When Guardiola repeatedly asked for more from Aguero during his fraught first few months in charge at City, this performance is exactly what he had in mind. Sure, the club's all-time record goalscorer is a penalty box thief of the highest order, but there is more to his game and Brighton were subjected to the full repertoire. Aguero dribbles from deep created both goals and he deserved to be on the end of Sterling's pass to seal the points. A typically warm embrace from his manager followed when he was substituted to a standing ovation.
ALL THE pic.twitter.com/vrFgyILlNZ— Manchester City (@ManCity) September 29, 2018
Locadia misses chance to impress
Chris Hughton left Brighton's attacking talisman Glenn Murray on the bench and gave Jurgen Locadia a first start of the Premier League season. A bright beginning from the visitors meant the former PSV favourite had more opportunities to shine than he might have expected, but he was well marshalled by Aymeric Laporte and Nicolas Otamendi and his task soon became a thankless one.
Key Opta facts:
- Since winning back to back Premier League away games against West Ham and Swansea City last November, Brighton have collected just five points in 17 top-flight matches on the road (P17 W0 D5 L12).
- Aguero has scored 15 goals in his last 11 Premier League appearances at the Etihad Stadium.
- Sterling has been involved in 35 Premier League goals for City since the start of last season (22 goals, 13 assists), a figure bettered only by Mohamed Salah (46) and Harry Kane (38).
- Sane has assisted more Premier League goals since the start of last season than any other player (17).
City will attempt to kick-start their Champions League bid in Hoffenheim on Tuesday after a surprise defeat to Lyon, with their eagerly anticipated trip to Anfield coming next weekend. Brighton are at home to a resurgent West Ham on Friday.