European Commission President Jean-Claude Juncker has informed the Lithuanian government about his appointment.
Pranckevičius has won a competition and is taking up his new post on October 17.
The head of the representation is appointed for a three-year term that can be extended for another two years.
With degrees in journalism and international relations, Pranckevičius served as adviser to European Parliament President Jerzy Buzek in 2009-2012 and has been advising EP President Martin Schulz since 2012. Prior to the positions, Pranckevičius worked in the EP External Policies Directorate General and was in charge of interparliamentary delegations (2006-2009) and of the performance of the Foreign Affairs Committee (2009). At the start of his career, he was interior policy adviser to Lithuania's President Valdas Adamkus in 2004-2005, the EC said.
Pranckevicius is the third Lithuanian appointed to the post, which has in the past been held by Kęstutis Sadauskas and Natalija Kazlauskienė.
In September, he was listed among four shadow foreign ministers of the conservative Homeland Union – Lithuanian Christian Democrats.