The Norwegian striker had only scored one goal in his previous five league games and also missed a penalty in City's heavy 4-1 defeat at Sporting Lisbon in the Champions League on Tuesday.
However, Haaland needed just 23 minutes to open the scoring against Brighton; City's No.9 received a brilliant through-ball from Mateo Kovacic, and although his first effort was stopped by Bart Verbruggen, he managed to poke home the rebound in off the crossbar.
Haaland was unable to add to his tally on the South Coast, though, and Brighton turned the game on its head within the space of just five second-half minutes, courtesy of substitutes Joao Pedro and Matt O'Riley.
Man City have now suffered four defeats in a row for the first time under manager Pep Guardiola, but Haaland can at least come away from the Amex with a fresh Premier League record to his name.
Indeed, Haaland has now scored 75 goals in 77 Premier League appearances and has reached that milestone in the fastest time in the division's history, surpassing the previous record held by Alan Shearer who scored his first 75 goals in 93 games.
Haaland nets record-breaking 75th PL goal in Brighton loss
Haaland has also scored 75 PL goals faster than Harry Kane (115 games), Ruud van Nistelrooy (116 games) Mohamed Salah (117 games) and City legend Sergio Aguero (118 games) who are next on the list after Shearer.
The 24-year-old is still leading the way at the top of the Premier League scoring charts this season, with his strike against Brighton moving him onto 12 goals in just 11 top-flight games, four more than his nearest challenger Bryan Mbeumo (eight).
Haaland's latest goal is also his fourth in as many league games against Brighton, and his first at the Amex Stadium after failing to make the net ripple in his previous visit in May 2023 (1-1 draw).
Indeed, Haaland has now found the net at 19 of the 21 stadiums he has played at in the Premier League, only failing to do so against Liverpool at Anfield (two games) and Brentford at the Gtech Community Stadium (one game).
Haaland's efforts up front against Brighton on Saturday were ultimately not enough for City to come out on top, though, and the striker has now suffered defeat in a Premier League match in which he scored a goal for the very first time, having won 40 and drawn six of the previous 46 he had scored in.
Man City, who remain second in the Premier League table, will hope that Haaland is both fit and back to his prolific best when they welcome Tottenham Hotspur to the Etihad Stadium for their first Premier League game after the international break in November 23.