Montassar Talbi was born on 26 May 1998 in Paris, France, to Tunisian heritage. He came through ES Tunis youth football and won the Tunisian Ligue 1 in 2016–17 and 2017–18, plus the Arab Club Champions Cup in 2016–17, with the senior side. After moves to Çaykur Rizespor (free 2018), Benevento (free 2021), and Rubin Kazan (€900K Aug 2021), he joined French side Lorient in July 2022 for around €1.5 million.
His Lorient career has been notable. The 2022–23 Ligue 1 season brought 25 league matches; after Lorient's 2024 relegation he played 29 Ligue 2 matches with 1 goal as Lorient won the 2024–25 Ligue 2 title and earned promotion. The 2025–26 Premier League debut season has been productive: 27 league matches with 1 assist.
For Tunisia, Talbi has been a senior centre-back across multiple AFCON and World Cup qualifying campaigns. He scored a goal in 4 AFCON 2025 matches and continues to be one of the senior central defenders in the Tunisia setup.
A 190cm two-footed centre-back with the height to dominate aerially, ball-playing security and the leadership of a senior squad member, Talbi is one of Tunisia's most experienced central defenders heading into the 2026 FIFA World Cup, alongside Yassine Meriah and Dylan Bronn.