The 23-year-old completed a stunning season that also saw him score 22 goals in the league as Dortmund cruised to their second consecutive Bundesliga title earlier this month.
His performance on Saturday against Champions League finalists Bayern was another warning to Euro 2012 co-host Poland's Group A rivals Greece, Russia and Czech Republic.
"We played a very good season and today we topped it off with the Cup," the softly-spoken Lewandowski, who joined Dortmund in 2010 from Lech Poznan, told reporters.
"It is a great feeling," he added.
The tall striker prefers to do his talking on the pitch and, after playing second fiddle to Paraguay's Lucas Barrios last season, grabbed the starting spot in Dortmund's record-breaking campaign as they finished ahead of Bayern on 81 points.
Lewandowski again had perfect timing on Saturday, grabbing his first deep in first-half stoppage time when he slotted home through goalkeeper Manuel Neuer's legs to give his team a 3-1 lead.
Lewandowski killed off any lingering Bayern hopes with a header at the far post as he finished his club season knowing he will again be coach Jurgen Klopp's first choice next term with Barrios conceding defeat in their rivalry and leaving for China.
"This is an indescribable year for us and this is the cherry on top," said Dortmund captain Sebastian Kehl.
