While Vani's popularity continued to soar in Bollywood cinema, she started getting offers from the South Indian industry. In 1973, she recorded her first Tamil song for the film "Thayum Seiyum" under the music direction of S. M. Subbaiah Naidu. However, the film remains unreleased till date and the song remained in the cans. Her first released song was a duet romantic song with T. M. Soundararajan for the film "Veettukku Vandha Marumagal" (1973). The song "Or Idam Unnidam" was composed by the duo Sankar Ganesh, with whom, Vani went on to record maximum songs in Tamil cinema. Immediately after this, she was employed by one of the most successful director-composer duos, K. Balachander and M. S. Viswanathan, for their successful film "Sollathaan Ninaikkiren" for a solo song "Malarpol Sirippathu Pathinaaru". Thus began her long association with the top rated music directors in Tamil cinema. Her biggest break came through the song "Malligai En Mannan Mayangum" from the film "Dheerga Sumangali" (1974), again composed by M. S. Viswanathan. The song received laurels and accolades for both its composition and vocal rendition. It was in the same year, she recorded a duet song with S. P. Balasubrahmanyam for music director Vijaya Bhaskar for the film "Engamma Sapatham". It was later reported that Vani's voice featured in all the films which had Vijaya Bhaskar as the composer in both Tamil and Kannada film industries.