An early morning meeting of party MLAs here elected her unanimously, party sources said.
Party Treasurer and Chief Minister O Panneeerselvam forwarded the motion to elect her as legislature party leader which was seconded by Electricity Minister Natham R Vishwanathan, the sources said, adding, it was adopted unanimously.
A beaming Cooperative Minister, Sellur K Raju, when asked if Jayalalithaa had been elected as LPP leader, said: "this is the happiest day of our life."
The Karnataka High Court had subsequently acquitted her of the charges on May 11.
Jayalalithaa is later expected to stake claim for forming the government, with the resignation of incumbent Panneerselvam being a mere formality.