After playing in the Lithuanian 2nd Division with LKKA-Žalgiris, during the 2002–03 season, Jankūnas made his debut with the Lithuanian EuroLeague club Žalgiris Kaunas, in the 2003–04 season.
He was originally an early entry candidate for the 2005 NBA draft, before withdrawing his name from consideration.

Jankūnas averaged 13.8 points and 8.0 rebounds per game, in the 2008–09 EuroLeague season, and scored a season-high 23 points, in a win against the Polish League club Asseco Prokom Sopot, on 18 December 2008.
However, Žalgiris Kaunas finished the season with a 2–8 record, and did not qualify to the competition's Top 16 stage.
Jankūnas was named the 2008–09 season's Baltic League MVP, after averaging 15.4 points and 7.7 rebounds per game.
After playing in the Lithuanian 2nd Division with LKKA-Žalgiris, during the 2002–03 season, Jankūnas made his debut with the Lithuanian EuroLeague club Žalgiris Kaunas, in the 2003–04 season. He was originally an early entry candidate for the 2005 NBA draft, before withdrawing his name from consideration. 
Jankūnas averaged 13.8 points and 8.0 rebounds per game, in the 2008–09 EuroLeague season, and scored a season-high 23 points, in a win against the Polish League club Asseco Prokom Sopot, on 18 December 2008. However, Žalgiris Kaunas finished the season with a 2–8 record, and did not qualify to the competition's Top 16 stage. Jankūnas was named the 2008–09 season's Baltic League MVP, after averaging 15.4 points and 7.7 rebounds per game.
Paulius Jankūnas