Głowacki vs. Huck

On 14 August 2015, Głowacki won the WBO cruiserweight title, defeating Marco Huck (38-2-1, 26 KOs) by eleventh-round knockout. Huck dropped Głowacki with a huge left hand in the sixth round, Głowacki staggered to his feet and threw back everything he had, rocking Huck in the process. Coming into the eleventh round Huck was ahead on the scorecards, Głowacki knocked down Huck with a left-right combination. As the referee allowed the bout to continue, Głowacki landing two huge right hands and dropped Huck down against the ropes, the referee come in and waved off the bout. Glowacki twice dropped Marco Huck in a knockout that foiled Huck's attempt at a record 14th defense in the 200-pound division at the Prudential Center in Newark, New Jersey.^[4] Like Huck, it was Glowacki's first fight outside of Europe.^[5] Many consider this as the 2015 fight of the year.

Głowacki vs. Cunningham

On 16 April 2016, he defended the WBO cruiserweight title by unanimous decision (116-108, 115–109, 115–109) against Steve Cunningham. Cunningham was down twice in the second-round and once in tenth and twelfth.

Głowacki vs. Usyk

Głowacki lost the WBO cruiserweight championship against undefeated Ukrainian boxer Oleksandr Usyk (9-0, 9 KOs) on 17 September 2016 at the Ergo Arena in Gdańsk, Poland.^[6] The fight was shown live on Sky Sports in the UK. On the night, Usyk outpointed Głowacki after an exciting twelve-round fight with the judges scoring it 119–109, 117–111, and 117–111 all in Usyk's favour.

Głowacki vs. Vlasov

On 10 November 2018 Głowacki won the vacant WBO interim title by unanimous decision (118-110, 117–110, 115–112) against Maxim Vlasov (42-2, 25 KOs)^[8] in the World Boxing Super Series cruiserweight quarter-final. Głowacki knocked Vlasov down in the third-round of the bout. The fight took place at the UIC Pavilion in Chicago, United States.

Glowacki vs. Briedis

On 6 February 2019 it was announced that Glowacki would challenge Latvia's Mairis Briedis (25-1, 18KOs) to defend the WBO interim title and their quest for the Ali Trophy in the cruiserweight division semi-final on 15 June at the Arena Riga in Riga, Latvia. On 4 June the WBC made Oleksandr Usyk 'champion in recess', which frees up the vacant WBC cruiserweight title to be on the line for the Briedis vs. Glowacki fight. On 5 June, after Usyk moved up to heavyweight, the WBO made Krzysztof Glowacki their new cruiserweight champion.^[9]

On 15 June 2019 in Riga he lost in third-round by TKO to Briedis. The fight raised a lot of controversy at the end of the second-round when, during a clinch, Glowacki punched Briedis in the back of the head. Briedis responded with an elbow to Glowacki's jaw. Glowacki fell down but was able to stand up and referee Robert Byrd continued the fight. Next the referee didn't hear the bell and Glowacki was punched by Briedis which was scored as a knockdown for Briedis. During the bout after the bell, which was not heard by a referee, some of the Briedis' crew entered the ring.^[10]

Głowacki vs. Okolie

At the WBO federation convention in Tokyo, it was decided that Głowacki would face Lawrence Okolie for the vacant cruiserweight title.^[11] Okolie won by stoppage to hand Głowacki his third defeat.^[12]

Głowacki vs. Francisco Rivas Ruiz

Głowacki won in a bout against Francisco Rivas Ruiz, via TKO.^[13]

Głowacki vs. Richard Riakporhe

Głowacki lost in a bout against British boxer Richard Riakporhe, via TKO. This bout was on the undercard of Chris Eubank Jr. vs Liam Smith, held in the Manchester Arena in Manchester, England, on the 21 January 2023.^[14] Almost a year after the bout it was announced that Głowacki tested positive for boldenone in the bout's urine sample, and was banned from any competition overseen by UKAD for four years.^[15]