The baby was born on Thursday noon.
The 66-year-old actress, who is married to actor Dharmendra, took to micro-blogging website Twitter to announce the news and share her joy.
"Thk u all for ur good wishes. Yes Ahaana has delivered a baby boy & we are all so thrilled! Mother & baba are fine," Hema tweeted.
Ahaana, a trained Odissi dancer, is the younger sister of actress Esha Deol, who hosted a star-studded baby shower for the former in March.
Even Esha shared the good news.
"Thank you all for the wishes! Yes Ahaana gave birth to a baby boy yesterday 11th June at noon! Both mother and son are in bliss," shared the "Dhoom" actress.
Ahaana tied the knot with Delhi-based businessman Vaibhav Vohra on February 2, 2014.