[8] After signing a new three-year contract in May 2016,[11] Bech made 10 appearances during the 2016–17 season and scored his first senior goal with a consolation in a 3–1 DBU Pokalen last-16 defeat to AGF Aarhus on 15 March 2017.

[5] Injuries to first team central defenders John Egan, Andreas Bjelland and Chris Mepham saw Bech feature as an unused substitute on five occasions during the 2017–18 season.

[8] He battled with homesickness during the season and adjusting to life in London, but received support on the field from Danish teammate Andreas Bjelland and off it from the club's sleep coach.

[12] Bech was promoted to the first team squad for the 2018–19 season and made his debut for the club with a start in an EFL Cup first round match versus Southend United on 14 August 2018.

[15] A season-ending injury suffered by central defender Yoann Barbet in late March 2019 allowed Bech to break into the starting lineup and he finished the 2018–19 season with 10 appearances.

[25] After beginning the 2020–21 season restricted to EFL Cup appearances,[26] by November 2020, injury and illness suffered by central defenders Pontus Jansson and new signing Charlie Goode respectively allowed Bech to break into the league lineup alongside Ethan Pinnock.

[7] He started all but one match of Brentford's run to the EFL Cup semi-finals and became the first team's throw-in specialist,[7][26] after having received further coaching from Thomas Grønnemark and extending the length of his throws to 40 metres (44 yd).

[26] Injury to left back Rico Henry in February 2021 saw Bech deployed in the position until head coach Thomas Frank switched to a 3-5-2 formation in mid-April,[28][29][30] at which time he dropped out of the starting lineup.

[31] Bech returned fit for Brentford's 2021–22 pre-season and began the regular season fourth in the central defensive pecking order behind Pontus Jansson, Ethan Pinnock and new signing Kristoffer Ajer.

[32] He returned to the matchday squad in late November and had to wait until 22 December to make his comeback,[33] with a start in a 2–0 EFL Cup quarter-final defeat to Chelsea.

[8] The departure of Charlie Goode on loan and injuries suffered by Ethan Pinnock and Zanka allowed Bech to start in Brentford's final five Premier League matches of the season.

[53] Bech won his maiden call into the Denmark U18 squad in September 2016 and made 7 appearances during the 2016–17 season,[4] captaining the team and scoring once in a 4–2 friendly victory over Belarus U18 on 18 October.