In a letter to Sounderarajan, the CM expressed happiness over her appointment as the state unit President, an official release said.
"I congratulate you on your appointment as President, BJP Tamil Nadu unit," she said.
Karunanidhi also congratulated H Raja and Lalitha Kumaramangalam on their appointment as National Secretary and National Spokesperson and said it was an opportunity given to them to work for the party.
"I consider their appointments an opportunity for them to work more. They have been working to develop the party in Tamil Nadu for a long time and the appointments have come at the right time," he said in a message to the three leaders.
"On behalf of DMK, I congratulate them on their appointments", he said in a party statement.
BJP's allies in the state DMDK and PMK also greeted Sounderrajan.
DMDK Chief Vijayakant, in a statement, congratulated Sounderrajan for becoming the first woman President of BJP Tamil Nadu unit and also extended his greetings to H Raja.
PMK President Ramadoss said Sounderrajan's appointment was a reward as she has served in various party posts in BJP. He too congratulated Raja.
Yesterday 53-year-old Sounderrajan, who was earlier BJP National Secretary was appointed as Tamil Nadu unit president, replacing Pon Radhakrishnan.