Speaking after meeting the DMK leader, Khushboo, 40, told reporters that she had made the right decision.
"I think I have made the right decision. It was completely my decision. I love to serve the people. That is what made me join politics, " she said.
Asked if she desired to be elected to the Tamil Nadu assembly or parliament, she said: "Since I have joined the party, I will leave it to the chief minister to decide what position he wants to give me."
Khushboo told earlier that she had always wanted to involve herself in full-time politics.
"I have always had the greatest of regards for Kalaignar's leadership qualities. I am extremely happy to be aligning with the DMK, " she said, referring to the chief minister the way he is addressed by admirers.
Khushboo was last month acquitted by the Supreme Court in all 22 cases pending against her in courts across Tamil Nadu for endorsing pre-marital and live-in relationships.
She started her career in the 1980s as a child artist with "Thodisi Bewafaii" and next year she did "Laawaris".
She was introduced to southern film industry by K. Raghavendra Rao's Telugu movie "Kaliyuga Pandavulu". She worked in all four southern movie industry but was more active in Tamil films.
Some of her films are "Ranadheera", "Anjada Gandu", "Shanthi Kranthi" and "Yugapurusha". After ruling the Tamil film industry in the 1990s, she tied the knot with director Sundar C who later became an actor.
Long after she fell out of favour with producers due to her age, she remained in touch with her fans, who built a temple for her here, through her hugely popular show "Jackpot" on Jaya TV.
The show has been running for more than eight years.