Early career Mahieddine made his professional debut against Issam Reghi at Kickboxing Championnat D'Europe on December 19, 2008. He won the fight by decision. He would go on to amass a 12–5 record, mostly competing on the French circuit, before beginning to compete in European tournaments. Mahieddine faced Bas Vorstenbosch in the semifinals of the K1 Event 8 heavyweight tournament, held on February 20, 2016. He beat Bas by decision. He won the tournament with a decision victory against Abderhamane Coulibaly in the tournament finals. Mahieddine was scheduled to face Marco Manetti at Boxe Evenements 13 on March 26, 2016. He won the fight by a first-round knockout. Mahieddine took part in the Partouche Kickboxing Tour heavyweight tournament, held on July 22, 2016. He was scheduled to face Farid Nair in the tournament semifinals. It was the third overall meeting between the two, with Mahieddine both of their previous fights. Mahieddine was as successful in their third encounter as he was in the first two, winning by a first-round knockout. He fought Dragos Zubco in the finals, and won by a third-round knockout. Mahieddine made his Glory debut against
Nicolas Wamba at
Glory 35: Nice on November 5, 2016. Wamba won the fight by decision. Mahieddine fought Saša Polugić for the
WAKO European Heavyweight title at XI eme Trophée Des Etoiles on April 8, 2017. He won the fight by a third-round knockout. Mahieddine was scheduled to face
Peter Aerts at the April 23, 2017 event. Aerts won the fight by decision. Mahieddine was scheduled to fight
Daniel Sam at Capital Fights 2 on May 20, 2017. Sam won the fight by decision. Mahieddine fought
Tarik Khbabez at the October 29, 2017, event. Khbabez won the fight by decision. Mahieddine was scheduled to face
Roman Kryklia at the November 25, 2017 NDC event. Kryklia won the fight by decision. Mahieddine took part in the 2018 World Fighting League heavyweight tournament, held on September 22, 2018, and was scheduled to face
Fred Sikking in the quarterfinals. He beat Sikking by decision, and beat
Andrei Stoica in the semifinals in the same manner. Mahieddine lost to
Murat Aygün in the tournament finals by decision.
GLORY Mahieddine made his second appearance with the promotion against
Antonio Plazibat at
Glory 66: Paris on June 22, 2019. Plazibat won the fight by unanimous decision. Mahieddine was scheduled to face Kiril Kornilov at
Glory 70: Lyon on October 26, 2019. He won the fight by unanimous decision. Mahieddine was scheduled to fight
Cihad Kepenek at
Glory Collision 2 on December 21, 2019. He won the fight by split decision, after an extra round was fought. Mahieddine participated in a four-man, one night tournament at
Glory 76: Rotterdam on December 19, 2020. He fought a rematch with
Antonio Plazibat in the semifinals, while the other semifinal pairing consisted of
Levi Rigters and Marciano Bhagwandass. Mahieddine beat Plazibat by a close split decision, after an extra round was fought, and faced Rigters in the tournament finals. Rigters won the fight by a first-round knockout. Mahieddine was scheduled to face Raul Cătinaș at
Glory 78: Rotterdam on September 4, 2021. He won the fight by unanimous decision. Mahieddine was booked to rematch
Cihad Kepenek at
Glory 81: Ben Saddik vs. Adegbuyi 2 on August 20, 2022. He lost the fight by a first-round knockout. The result was overturned to a no contest on November 24, as Kepenek tested positive for a banned substance. Mahieddine made his light heavyweight debut against
Felipe Micheletti at
Glory 84 on March 11, 2023. He lost the fight by unanimous decision. Mahieddine faced
Abdarhmane Coulibaly at
Glory 88 on September 9, 2023. He won the fight by a third-round knockout. Mahieddine was expected to face
Benjamin Adegbuyi in a reserve Heavyweight Grand Prix at
Glory Heavyweight Grand Prix on March 9, 2024. He later withdrew from the bout, as Glory placed him in the
Glory Heavyweight Grand Prix as a replacement for the injured
Antonio Plazibat. Mahieddine was expected to face Nabil Khachab in the Grand Prix quarterfinals on March 9, 2024. He was pulled from the fight by the promotion. Mahieddine faced Nikola Filipović at
Glory 95 on September 21, 2024. Mahieddine faced
Antonio Plazibat in a rematch at
Glory Collision 8 in a
Glory Last Heavyweight Standing Finals Tournament qualifier on December 13, 2025. He lost the fight by unanimous decision. ==Championships and accomplishments==