The 45-year-old politician from North Rhine-Westphalia received 89 percent of the votes at Saturday’s federal party conference in Berlin.
He has been acting General Secretary since December after the board and committee approved FDP leader (and German Finance Minister) Christian Lindner’s nomination of him for the post.
He is succeeding Volker Wissing, who is Digital and Transport Minister in the new coalition government.
Djir-Sarai said he would “never, never, never” be a government spokesman.
“My mission is FDP. My mission is a successful FDP,” he said.