In New Delhi, lives the Kaushik family. Mr Jeetendra Kaushik (Gajraj Rao), a Railway TC, Mrs Priyamvada Kaushik (Neena Gupta), the outspoken housewife who spends her time caring for her physically ailing but mentally feisty mother-in-law, Maaji (Surekha Sikhri), the younger son, Gular, 16 (Shardul Rana), who is detached from the family like any other teenager, and the elder son, Nakul, 25, (Ayushmann Khurrana) who works in a corporate and is trying to step up the economy ladder.
News breaks out that the mother is pregnant which comes like a shock to the entire family. To top it, they also have to deal with the social embarrassment – friends, relatives, neighbours, everyone's gaze is now turned towards the Kaushik household. It is the elder son, Nakul, in particular who wasn't really looking forward to this new addition in the family. Badhaai Ho is a story of Nakul's coming of age and the family coming together as they try to grapple with the good news in their own unique way and prepare to welcome the new unexpected member home.