[8] Growing up in Cieszyn, Poland, Błachowicz started training martial arts – initially judo at the age of nine – due to the influence of action movies, he also did grappling, muay thai achieving 34 wins in muay thai and won tournaments in both sports before transitioning into mixed martial arts.

Looking to expand his horizons after the very successful year 2008, Błachowicz accepted the invitation of Tomasz Drwal and joined him at the Throwdown Training Center in San Diego for a few months.

He agreed to temporarily fight at Heavyweight, against Lloyd Marshbanks under the War Gods banner, but the event was canceled.

Despite suffering a serious knee injury in July, Błachowicz continued his training, as he agreed to fight "somewhere in Mexico".

[11] Błachowicz was planning his comeback fight in March against Aleksandar Radosavljevic at WFC 10, but decided to withdraw and was replaced by fellow KSW TEAM member Antoni Chmielewski.

After finally returning from the knee injury and 17 months layoff,[11] Błachowicz entered into the second KSW <95 kg tournament.

In the semifinal, Błachowicz submitted his training partner Wojciech Orłowski with a rear-naked choke after just 1:37.

[12] In the meantime, Błachowicz took a fight on a few days notice against Nikolai Onikienko and submitted him in the second round.

He lost the fight via TKO, being unable to answer the bell for the third round because of his injured leg.

His next three fights in KSW were against Mario Miranda, Houston Alexander and Goran Reljic, and all three he won by unanimous decision.

In January 2014, after completing a 17–3 record on the European scene, Błachowicz signed a contract to fight in the light heavyweight division of the UFC.

[19] However, Johnson was pulled from the bout on July 30 in favor of a fight with Jimi Manuwa at the event.

[26] Błachowicz was expected to face Ovince Saint Preux on February 4, 2017, at UFC Fight Night 104.

[27] However, he pulled out on January 21 due to injury and was replaced by promotional newcomer Volkan Oezdemir.

[42] Błachowicz was caught with a counter in the third round and lost by TKO, marking the first time in his MMA career that he has been stopped due to strikes.

[48] Błachowicz faced Corey Anderson on February 15, 2020, at UFC Fight Night 167 in a rematch of their previous bout.

[61] However, in late January, Błachowicz withdrew due to injury[62] and the bout was rescheduled for UFC on ESPN 36 on May 14, 2022.

[63] Błachowicz won the fight via technical knockout after Rakić was rendered unable to continue in the third round due to a knee injury.

He also occasionally trains in Alliance MMA with names such as Alexander Gustafsson, Phil Davis, Joey Beltran, and Dominick Cruz.