*Club domestic league appearances and goals, correct as of 23:05, 21 May 2024 (UTC) ‡ National team caps and goals, correct as of 23:28, 29 June 2024 (UTC)
Born in Østervrå, Vendsyssel, Mæhle started playing football with local club Østervrå IF and moved to the AaB youth academy as a 12-year-old.[3] At the age of 19, Mæhle was promoted into the first team squad on 10 June 2016 and also signed a full-time senior contract with AaB.[4] He made his debut for AaB on 7 August 2016.[5] He started on the bench, but replaced Thomas Enevoldsen in the 89th minute in a 2–1 victory against FC Nordsjælland in the Danish Superliga.
On 11 November 2016, Mæhle earned a new contract until 2020.[6] In April 2017, AaB confirmed that they were in negotiations with a foreign club about Mæhle.
Genk
On 9 May 2017, AaB confirmed that they had sold Mæhle to Belgian club Racing Genk for an undisclosed fee, starting from 1 July 2017.[3] He was signed to succeed right-back Timothy Castagne, who had moved to Atalanta. Mæhle made his debut for Genk on 29 July 2017 in the first league match of the season against Waasland-Beveren as a substitute for Amine Khammas. In his first season with the club, he was not a fixed starter, competing with Clinton Mata for his position. In his second season, after Mata's departure to Club Brugge, he won a permanent starting position. That season, Mæhle grew into a key player in the Genk starting eleven. At the end of the season, Genk won the Belgian championship.
On 11 September 2019, Mæhle extended his contract until June 2023.[7]
Atalanta
Genk announced on 22 December 2020 that Mæhle had signed for Atalanta on a five-year contract for a fee of €10 million. His transfer was made official on 4 January 2021.[8] He made his Serie A debut for Atalanta on 6 January in the club's 3–0 win over Parma.[9] On 28 February, Mæhle provided an assist in Atalanta's 2–0 win over Sampdoria.[10] Mæhle scored his first goal for Atalanta in a 6–2 Serie A victory over Udinese on 9 January 2022.[11]
VfL Wolfsburg
In August of 2023, Mæhle joined VfL Wolfsburg for a fee of reportedly around €12 million.[12] On September 6th, 2023, he scored his first goal for the club in a 2-1 win against 1. FC Union Berlin.[13]