Blaszczykowski extends Dortmund contract
The Poland international, who joined in 2007, has been a key player for Dortmund, helping them to two consecutive German league titles in 2011 and 2012 as well as a German Cup win last year.
"Kuba is a crucial part of the team both on a sporting and a personal level," sports director Michael Zorc said in a statement.
The 27-year-old also helped his team to the Champions League final this season where they lost 2-1 to Bayern Munich last month as well as second place in the Bundesliga behind their treble-winning rivals.
"When my contract runs out I will have been at the club more than a decade. Such long stints are not common in professional football these days and I am proud to have this trust from my club," he said.
Dortmund will again compete in next season's Champions League group stage.