Larouci was captain of Le Havre's U18 side. After rejecting their contract extension he subsequently became a free-agent and moved to Liverpool in 2017. The winger turned left-back was part of Liverpool's USA pre-season tour in the summer of 2019 and on the substitutes' bench when Liverpool faced Arsenal in the fourth round of the Carabou Cup on 30 October 2019. Against Everton in the third round of the FA Cup, he got an opportunity when James Milner was forced off injured on the ninth minute. He then played all ninety minutes of the fourth round replay against Shrewsbury.

Larouci declined Liverpool's contract offer in the summer of 2021 and became a free agent. He joined French Ligue 1 side Troyes. In July 2023, Sheffield United signed Larouci on a season-long loan with an option to make the deal permanent. It was a disappointing campaign for both however with Larouci making just six league starts as the Blades finished bottom of the table. He was loaned to Watford for 2024/25. Larouci had a steady season in the Championship, making 39 appearances and making providing two assists. A groin injury in early April looked like it had brought his season to a close, but he was fit again to come on as a substitute in the final game. In September 2025, Larouci joined Greek Super League club Kifisias on loan for the remainder of the season.