Randers Bager is a product of
Randers FC's youth academy. In winter 2015 Bager went on a training camp with the first team squad to Spain. He made his first team debut on 9 July 2015 against Andorran club
UE Sant Julià in the
UEFA Europa League qualifiers; Randers won 3–0. He came on the pitch in the 76th minute, where he replaced
Johnny Thomsen. Later in the same season, Bager also made his debut in the
Danish Superliga against
FC Nordsjælland on 28 November 2015. He was officially promoted to the first team in October 2015. Bager's contract was extended in September 2016 until 2020.
Union SG In May 2019, Bager signed a three-year contract with
Belgian First Division B club
Union Saint-Gilloise. He made his debut for the club on 10 August as a substitute in stoppage time for
Teddy Teuma in a 1–0 away win over
Virton. During his first season at the club, he was mostly a substitute, making 8 total appearances. As he finished the season with 22 appearances, in which he scored 2 goals – both against Club NXT – Union Saint-Gilloise managed to win promotion to the
Belgian First Division A as champions. On 25 July 2021, Bager made his debut in the
Belgian First Division A as a starter, providing an assist for
Jean Thierry Lazare in a 3–1 away win over
Anderlecht.
Sporting Charleroi Bager joined
Sporting Charleroi on 13 July 2022, signing a two-year contract with an option for an additional two years. He made his competitive debut for the club on 23 July, the first matchday of the season, coming on as a substitute in the 87th minute for
Stefan Knezevic in a 3–1 home win. On 11 February 2023, he scored his first goal for Charleroi, heading home a
Damien Marcq corner-kick in a 3–0 league victory against
Seraing. He suffered a calf injury in late February 2023, which kept him sidelined for a month, and he returned to practice on 28 March 2023.
IFK Göteborg Bager joined Swedish club
IFK Göteborg on 16 July 2024, signing a three-and-a-half-year contract. ==International career==