The producer has previously made Wake Up Sid! and Delhi Belly.
He told followers on Twitter: "I am going to be 40 in May... and filming with these 20 plus actors has made me realise that this is definitely my last stint at a 'young' film!
"At heart, I think I was born old... even at 25, I felt more easy directing the second half of Kuch Kuch Hota Hai."
Johar added: "The three kids in Student of the Year are lovely!!! Sid[dharth Malhotra] has a silent strong charm....Varun [Dhawan] has a real fun bratty appeal... Alia [Bhatt] is vivacious and super cute!!!"
The film will be ready for release this autumn, according to the veteran filmmaker.
In February, Shahid Kapoor revealed that he is keen to work work with Johar on his next project.
Johar has also committed to making the follow-up to his hit comedy Dostana this year.