Growing up, his favourite team was Barcelona, and his favourite player is Leo Messi. He enjoys playing FIFA, and plays as Bayern Munich. He is still very active outside of football, and enjoys playing padel tennis and tennis. Mads' favourite artist is J Cole, and he watched The Untouchables and Prison Break in his free time. His favourite food is any Japanese food. In the future, Mads wants to travel the world!

Mads started his career in Denmark with Østbirk IF, before moving to the AC Horsens academy.

In May 2015, he made his debut for the senior side as the Club's youngest ever player aged 16 years, three months and 26 days old.

The next two seasons saw the tall defender make several appearances in the Horsens squad, with most of his minutes coming from the bench. 

In March 2017, he scored his first professional goal in a Danish Cup match against Aarhus. A few months later, he netted his first Danish Superliga goal during a 4-1 win over Lyngby.

On 31 July 2017, Mads Bech joined Brentford on a four-year contract. His maiden call-up to the First Team came in September later that year, when injuries to John Egan and Andreas Bjelland saw him as unused substitute in The Bees' 2-2 draw with Middlesbrough.

He was promoted to the First Team the following season, making his debut in the EFL Cup victory over Southend United in August 2018. Injuries restricted his playing time for the rest of the season until a spell at the end of the campaign, which meant he ended up with a total of 10 games that term.

Another injury kept him out of the early stages of the following season but he recovered to head out on loan to AFC Wimbledon. He would make nine appearances before the Covid Pandemic cut short the League One season.

He played a big role as backup in the 2020-21 season, which would culminate in Brentford's promotion to the top-flight. He also helped The Bees to their first major cup Semi-Final when they played Tottenham in the EFL Cup, starting all but one match on the road to North London.

His first Brentford goal came in an FA Cup defeat to Leicester City, in snowy conditions they lost 3-1 to the eventual champions. An injury to Rico Henry saw Mads deployed at fullback for a short time. At the end of the campaign, he had accrued 39 games and netted three goals.

Sørensen appeared in six of Denmark's 10 matches during the U21 team's successful 2021 European U21 Championship qualifying campaign and he was named in the squad for the tournament finals. He started each of Denmark's group matches and scored in a 2–0 win over Iceland U21 on 28 March 2021. Injury saw him miss out on the knockout stages, though his group stage peformances were such that he was named in the Squad of the Tournament.

He came on as a sub during Brentford's first ever Premier League fixture, a 2-0 win over Arsenal, to set up the second goal via a long throw nodded home by Christian Nørgaard.