Emreli made his professional debut in the
Azerbaijan Premier League for
FC Baku on 27 September 2014 in a game against
Araz-Naxçıvan.
Qarabağ On 16 July 2015, Emreli signed a three-year contract with
Qarabağ FK. On 23 August 2015, Mahir made his debut and scored his first goal for Qarabağ in a 2–0 away victory against
Shuvalan. Emreli made his European debut in 2016 against Luxembourgish
F91 Dudelange in the second qualification round of the
UEFA Champions League which ended 2–0 for Qarabağ. On 15 September 2016, Emreli made his debut for
UEFA Europa League group stage game against
FC Slovan Liberec. He scored his first European goal in a 1–0 home victory against Danish
Copenhagen in the play-off round of the
2017-18 UEFA Champions League. Emreli made his debut for
UEFA Champions League group stage game against
Chelsea in
Stamford Bridge on 12 September 2017. Mahir made five appearances in the
UEFA Champions League group stage. On 18 August 2020, Emreli, scoring against
FK Sileks at the
first qualifying round of the UEFA Champions League, celebrated his goal with a
salute to the Azerbaijani soldiers serving in the frontline during the
border clashes with
Armenia.
Legia Warsaw On 8 June 2021,
Legia Warsaw announced the signing of Emreli on a contract until 30 June 2024. On 17 June 2021, Emreli made his debut and scored his first goal for Legia in a 5–0 friendly victory over
SK Bischofshofen. He scored his first officials goals for Legia in a
UEFA Champions League first qualifying round match against
Norwegian champions
Bodø/Glimt on 7 July 2021. On 26 August 2021, during
play-off match of the
2021–22 UEFA Europa League against
Slavia Prague, following an unsuccessful 0–1 first half, Emreli scored two goals and secured Legia's qualification to the
group stage of the tournament. He set a unique record by scoring in all the tournaments he participated in. In December 2021, Emreli was one of the victims of an attack by hooligans on a bus returning after the
Ekstraklasa match against
Wisła Płock. After this incident, Emreli decided not to play for Legia. On 2 February 2022, he terminated the contract by mutual agreement.
Dinamo Zagreb Hours after leaving Legia, Emreli was announced as the new player of
Dinamo Zagreb in the
Croatian First Football League. Legia owed Dinamo one million euros because they bought
Lirim Kastrati from them in September 2021 for 1.2 million euros, but by December 2021 Dinamo had received only 200,000 euros. Dinamo decided to drop Legia's debt on the condition that Emreli would leave Legia for free and sign for Dinamo. On 24 August 2022, Emreli played in the
play-off match against
FK Bodø/Glimt with Dinamo Zagreb winning 4–1 and ensuring a place in the
2022–23 UEFA Champions League group stage.
Loan to Konyaspor On 14 February 2023, Emreli was loaned to
Süper Lig club
Konyaspor until the end of the 2022–23 season with an option of a permanent transfer at the end of the season.
1. FC Nürnberg On 6 August 2024, Emreli joined German
2. Bundesliga club
1. FC Nürnberg. ==International career==