Shahrukh said he was "pleasantly surprised" when the STAR network offered him the show but admitted it would be "a huge act to follow" in the footsteps of Amitabh, who made "KBC" one of the country's most watched TV programmes.
Samir Nair, CEO of the Star India channel that airs the show, told PTI in Mumbai, "Mr Bachchan expressed his disinclination to do the show and we respect his decision. We are indebted to him for what he brought to the show but now it is time to move on and who better to hand over the baton to than Shah Rukh Khan.
"We have been in talks with Shah Rukh Khan for over a month now and he expressed his willingness to do the show. Shooting will begin by December-end and we expect this season to be on air by January-end," Nair said.
Shah Rukh Khan was quoted in a Star India release as saying, "I was pleasantly surprised when STAR offered me the show. I was a participant in season one of KBC... and little did I know one day I would be hosting it.
"It is a huge act to follow, that of Mr Bachchan... but it also excites me that I am getting an opportunity to reach out (and) talk and interact with my audience through a medium where I began my career as an actor years ago."
The hugely popular show, characterised by Bachchan's baritone and personality, was in its second season when it had to be cut short due to the star's sudden illness.
Since then Star had been in talks with Bachchan for the next season of the show based on "Who Wants To Be A Millionnaire", but those fell through.
Nair said the contract with Shahrukh would be for two seasons with an option to extend it further if required. He declined to comment on the pay for Shahrukh, saying, "It is adequate."
"Shahrukh will bring to the show boundless energy and his own unique personality that will make it a new KBC all together. We will not be calling this season three in particular.
"However contestants who were not allowed to participate in the second season will be allowed to compete in this season," he said.
