[3] Adamek won the vacant WBC light-heavyweight title defeating Paul "Firepower" Briggs by majority decision on 21 May 2005.

After losing to Dawson, Adamek moved up to cruiserweight to beat Luis Andres Pineda by technical knockout in round seven.

Knocking a game Cunningham down three times, he won the IBF and vacant lineal cruiserweight titles in a bout many thought was the fight of the year.

He then went on to defeat Bobby Gunn before a large crowd at the Prudential Center on 11 July 2009, with the referee stopping the bout at the ring physician's advice between rounds four and five.

[5] On 24 October 2009 in Łódź, Poland, Adamek defeated Andrew Golota by TKO in the fifth round to win the IBF "International" Heavyweight Title.

[7] On 10 September 2011 Adamek faced the WBC heavyweight champion Vitali Klitschko in Poland, losing by TKO in the 10th round, in the first ever PPV fight in Polish TV history.

Adamek returned on 24 March 2012, after signing a contract with Main Events, defeating Nagy Aguilera by unanimous decision.

During the first round, Chambers torn his bicep in the left arm,[13][14] and often switched between orthodox and southpaw stances throughout the rest of the fight, throwing shots almost exclusively with the right hand, mostly connecting with overhand punches.

The bout lasted full twelve rounds, with Adamek being declared the winner by unanimous decision with scores 116–112 (twice) and 119–109.

Initially, the result was a draw, but after noticing a mathematical miscalculation in the judges scorecards, Adamek was declared the winner.

[19] On 15 March 2014 Adamek was defeated by Vyacheslav Glazkov by unanimous decision after 12 rounds, losing his IBF North American heavyweight title.

[24] On February 24, 2024, in the main event of XTB KSW Epic: Chalidow vs Adamek, he fought Mamed Khalidov in a boxing match in the cage.