"I am the biggest fan of National Geographic Channel, so it means a lot to be here," John told reporters during the unveiling of the channel's Unlock campaign.
As the face of the channel, John will be part of the campaign's film and related communications.
The essence of the campaign is that it is time to open the doors of the mind - it's time to 'Unlock'.
John says he is very adventurous.
"I just love snakes. I am very excited about pythons. If given a choice, I would like to live my life with mountains, tigers and snakes. I love jungles and want to explore it," said the actor, whose latest film "Madras Cafe" was a hit.