The actor spoke about his admiration of Rajinikanth at the event, which took place at Chennai's Sathyam Cinema on Monday.
"When I first came to Mumbai, he was shooting a film with Mukul Anand. I have wanted to meet him ever since. Now, to think that I am breathing the same air as him is an honour," Khan told journalists at the audio launch.
Khan performed to the Akon track 'Chammak Challo', which has been partly sung in Hindi, English and Tamil.
The song has reached number one in several territories, including the UK, on the iTunes World Songs charts.
The actor also posed for photos with Raavan director Mani Ratnam, as well as Santosh Sivan, Soundarya Rajnikanth and Abhirami Ramanathan.
Ra.One will reportedly open on the highest number of screens ever for an Indian film on October 26.
Watch a trailer for Ra.One below: