Early career Albrektsson made his debut in the Polish organization MMA Koszalin and won his first match via finish in the second round. It took a little over a year after the debut before the next match ended.
International Ring Fight Arena Albrektsson started playing matches within the Swedish organization IRFA in 2013 and went undefeated, 3–0, through his time with them for a total result of 4–0 and was then picked up by the Japanese organization
Rizin FF.
Rizin Fighting Federation He made his debut on 17 April 2016 in
Rizin 1, played a hard and even match against the Russian
sambo world champion and later
Bellator champion,
Vadim Nemkov who Albrektsson finally defeated via a split decision. On September 25 of the same year, Karl faced
Valentin Moldavsky at
Rizin World Grand Prix 2016: 2nd RoundMoldavsky was the first to defeat Albrektsson in the latter's professional career. He did so by unanimous decision in an open-weight bout. Just over ten months later, it was time for Karl's next bout on July 30, 2017, at
Rizin Fighting World Grand Prix 2017 Opening Round Part 1. This time against
Lithuania Teodoras Aukstuolis who Albrektsson defeated via submission. At the World Grand Prix second match of the tournament on December 29, 2017, Albrektsson met Czech
Jiří Procházka who defeated him via TKO and knocked him out of the tournament. After that match, according to Albrektsson himself, he and Rizin had some trouble agreeing on matches. Albrektsson was supposed to meet
Conor McGregor's club mate,
Irishman Chris Fields 11 May at SC 19, but on May 3, 2019, it was reported that Albrektsson was forced to withdraw from the match due to injuries. His next bout for Rizin came against
Wanderlei Silva's student Christiano Frohlich at
Rizin 15 on April 21, 2019, which Albrektsson won by unanimous decision.
Bellator MMA / PFL MMA On July 30, 2019, it was announced that Albrektsson was signed to
Bellator MMA. Bellator was in contact with Albrektsson already in 2013, but he wanted to get a little more experience before signing for a larger organization and therefore waited until 2019. Albrektsson debuted in the organization on October 25, 2019, at
Bellator 231 against former Light heavyweight
Phil Davis in the co-main bout. Davis relied on his wrestling background and took down Albrektsson in rounds 1 and 2. In round 3, Davis beat Albrektsson with body blow and finished Albrektsson against the cage. Albrektsson faced
Viktor Nemkov, the brother of his previous opponent, at
Bellator 257 on April 16, 2021. He won the bout via unanimous decision. Albrektsson was scheduled to face Julius Anglickas on October 16, 2021, at
Bellator 268. After Anglickas replaced
Anthony Johnson in the LHW Grand Prix, Albrektsson instead faced
Dovletdzhan Yagshimuradov. He won by unanimous decision. As the first fight of his new multi-fight, multi-year contract, Albrektsson faced
Karl Moore on September 23, 2022, at
Bellator 285. He lost the fight via face crank submission in the second round. Albrektsson faced Grant Neal on February 4, 2023, at
Bellator 290. He lost the bout via split decision. 4 out of 6 media scores gave it to Albrektsson. After winning the Superior Challenge Light Heavyweight title against Ederson Cristian Macedo via first round TKO stoppage at Superior Challenge 26 on November 4, 2023, Albrektsson was set to defend his title against PFL veteran
Daniel Spohn on May 25, 2024 at Superior Challenge 27. However, the event was cancelled due to situation involving
Viaplay. Albrektsson was scheduled to face Laurynas Urbonavicius on June 21, 2024 at
PFL 5. however Urbonavicius pulled out and was replaced by
Ibragim Chuzhigaev. In turn, Chuzhigaev pulled out and was replaced by
Andrew Sanchez. Albrektsson was scheduled to face
Antônio Carlos Júnior on August 16, 2024 at
PFL 8. However the week of the bout, Albrektsson pulled out for unknown reasons. On March 4, 2025, the promotion officially revealed that Albrektsson will join the
2025 PFL Light Heavyweight Tournament. He lost the fight by technical knockout in the second round. Albrektsson returned to the tournament in an alternate bout as he faced PFL newcomer Rafael Xavier at
PFL 7 on June 27, 2025. He lost the fight via TKO in the first round. ==Mixed martial arts record==