"Johar and Dharma Productions will work exclusively with NDTV to achieve new levels of excellence in entertainment programming," the channel said in a press release.
"Karan will help originate concepts and new programming ideas and will be an ambassador for the NDTV entertainment brand," it added.
Dharma Productions will produce shows for the NDTV entertainment channel, which will have first right of refusal over these.
Johar will be on the board of NDTV's entertainment company, and Dharma Productions will hold an equity stake in it.
Speaking on the new alliance, NDTV chairman Prannoy Roy said: "We have enormous respect for Karan's brilliance and creativity...he is constantly breaking new ground in quality and transforming Indian movies to world class standards. We know he will now help us to redefine and set new benchmarks in entertainment television."
Johar said: "For me, this partnership is not just a professional association...it's a family bonding and I believe in the power of the family! What a family can do together no individual can do on his own."
The NDTV entertainment channel is being launched as part of the company's expansion beyond the news and business segments.
Johar and Dharma Productions have to their credit major blockbusters like "Kuch Kuch Hota Hai", "Kabhi Khushi Kabhi Gam", "Kal Ho Na Ho", and "Kabhi Alvida Na Kehna".