Blaszczykowski has a contract with Dortmund until 2018, having moved to the club in 2007 from Wisla Krakow in his native Poland.
In an interview with Ruhr Nachrichten, the 28-year-old winger praised the atmosphere at Dortmund, claiming the club is his "second home".
"I'm glad that I can play at such a big club. Dortmund is the second home for me and my family," Blaszczykowski said.
"And the BVB is always my number one."
The Poland international added: "We have a good atmosphere in the team. Players, coaches, physios, the doctor; it all fits together. And that makes us."
The man known as 'Kuba' admitted he was disappointed with Dortmund's performance last season, as Jurgen Klopp's team finished 19 points behind champions Bayern Munich in the Bundesliga.
Dortmund also lost the DFB-Pokal final to Bayern, finishing the campaign with only the 2013 DFL-Supercup to their name.
"After two [Bundesliga] championships [in 2011 and 2012] much has changed," Blaszczykowski said.
"2007, when I started here, we had no pressure. Fifth, sixth, that was okay.
"Now every year, the duty is to qualify for the [UEFA] Champions League. It is clear. We always want more achievements."