The 74 others in the case are accused, among other things, of "stuffing ballots for voters who had not voted and of signing for those people."
Dragnea was the mastermind, alleged the prosecutors, who filed the case in the Romania's top court, the High Court.
"He coordinated a complex information system through which he sent messages, orders and recommendations to stimulate citizens to vote through illegal methods via mayors, party activists and local authorities," the prosecution team said.
Dragnea is a member of the Social Democracy Party, which was at the time in the center-left opposition but now is in the governing coalition.
The then-opposition knew it could remove Basescu from office if more than half the electorate voted. But only 46 percent of voters turned out, rendering the referendum invalid.
The opposition Democratic Liberal Party called Monday for Dragnea to resign. He refused, calling the charges "unfounded" and "a blow to the foundations of democracy."
Prime Minister Victor Ponta, a Basescu rival, said the case was politically motivated.