He has earned the honour of twice being named the Polish Footballer of the Year by magazine Pilka Nozna in 2003 and 2004.

In the 2004–05 season, he was one of Leverkusen’s best players, and the trio of Krzynowek, Andriy Voronin and Dimitar Berbatov drew the attention of many top European sides.

In August 2005, he was part of the national team's triumphant performance at the Valeri Lobanovsky Memorial Tournament 2005.

As a result of another injury during the spring of 2006, he was unable to play regularly at his club, Bayer Leverkusen.

This was evident in his poor form during the 2006 FIFA World Cup and was one of the poorest performers in the Polish team as they lost 2–0 to the surprising Ecuador and 1–0 to hosts Germany.

Krzynówek was a key player in the UEFA Euro 2008 qualifying campaign for Poland where he scored four goals; three against Azerbaijan and an astonishing equalizer in the 87th minute against Portugal.

Thanks to a very successful all around performance he was then picked into Eurosport's dream team as the left midfielder and Poland's squad for UEFA Euro 2008 where the Poles competed for the first time in their history.

On 17 November 2007, Wisła Kraków announced that they were interested in purchasing Krzynówek during the Ekstraklasa transfer window, but after negotiations the Polish club could not agree to terms with VfL Wolfsburg.

On 15 August 2011, Krzynówek officially announced his retirement after 178 matches in the German top-flight.