[4] Cieślak made his professional debut on 29 June 2013, scoring a four-round unanimous decision (UD) victory over Lukasz Zygmunt at the Amfiteatr in Ostróda, Poland.
[6] Cieślak was booked to face Shawn Cox on 26 September 2015, on the undercard of a Polsat Sport pay per view broadcast card.
[8] Cieślak faced the one-time WBC cruiserweight title challenger Francisco Palacios on 2 April 2016.
[15] Cieślak secured another three wins, two by stoppage, before facing Ilunga Makabu for the vacant WBC cruiserweight title on 31 January 2020 at the Temporary Arena in Kinshasa, Democratic Republic of The Congo.
[18] Cieślak is scheduled to challenge the reigning WBO cruiserweight champion Lawrence Okolie in the main event of a DAZN broadcast card on 27 February 2022.