Johar, 44, has named his daughter Roohi and his son Yash, after his late father Yash Johar.
"I am ecstatic to share with you all the two most wonderful additions to my life, my children and lifelines; Roohi and Yash. I feel enormously blessed to be a parent to these pieces of my heart who were welcomed into this world with the help of the marvels of medical science," Johar said in a statement.
"In order to arrive at this decision, I have prepared myself mentally, physically, emotionally and logistically to ensure that my children get all the unconditional love, care and attention from me and mine. I have submitted to the fact that my children are my world and priority."
Johar says his work, travels and social commitments will have to take a back seat after the arrival of his kids and he is prepared for that.
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Thanking the surrogate, the filmmaker says he is eternally grateful to her as she has fulfilled his "lifelong dream and provided a warm, loving and nurturing environment to my children before bringing them into this world."
"She will always remain in my prayers. Finally, a big thank you to Dr Jatin Shah for his guidance and support and for being like a family member through this wonderful and exciting journey," he concludes.
Last year, actor Tusshar Kapoor welcomed a baby boy, who was born through in vitro fertilization (IVF) and surrogacy.
Johar's friend, superstar Shah Rukh Khan's third child, AbRam, was also born via a surrogate in 2013.