The filmmaker shared the news on his official Twitter handle and said, "I am ecstatic to share with you all the two most wonderful additions to mu life, my children and lifelines; Roohi and Yash."
Civic officials already said the births were registered with its public health department on Friday.
The twins, reportedly, were born at Masrani Hospital in Andheri (West) on February 7.
Interestingly, Karan Johar's close friend actor Shah Rukh Khan 's third baby, AbRam, too, was born in the same hospital to a surrogate mother.
Actor Tusshar Kapoor, in June 2016, had announced the birth of his son, Laksshya, through in-vitro fertilisation and surrogacy.