Signed in June 2022 as a reinforcement for the right flank, the Danish full-back was formed at Næsby Boldklub before making his way through the Danish game with HB Køge and SønderjyskE, where he was voted Talent of the Year in 2017.

A move to Slavia Prague in January 2021 proved decisive: he won the Czech league and cup double and was named the Czech First League's Defender of the Season in 2022, performances that persuaded SL Benfica to bring him to the Estádio da Luz on a five-year contract for a reported eight million euros.

Bah was a regular in the 2022/23 Primeira Liga title-winning side and has since added the Supertaça Cândido de Oliveira in 2023 and 2025 and the Taça da Liga in 2024/25, signing a renewal in December 2024 that ties him to the club until 2029. Quick, energetic and dangerous in the final third, he is equally comfortable as a full-back or as a right winger.

He made his Denmark debut in November 2020, scoring against Sweden on his first appearance, and has represented his country at the 2022 FIFA World Cup and UEFA Euro 2024, as well as being called up for the 2026 World Cup play-offs.