Shubh Mangal Saavdhan revolves around Mudit (Ayushman Khurana), Sugandha (Bhumi Pednekar) and their respective families. Mudit likes Sugandha but he is unable to express his feeling for her in fear of rejection. Sugandha also has a soft corner for him but she wants him to initiate the conversation. When Mudit realizes that he cannot propose her in real life, he relies on technology and sends a marriage proposal to her family.

Both families are happy to fix their marriage as they did not have to put in extra efforts to find their life partners. Everything seems to be hunky-dory until one day when Mudit and Sugandha come close and Mudit fails to perform in bed. He realizes that he has erectile dysfunction. He shares his problem with Sugandha and suggests her to break the engagement. Sugandha, who loves Mudit badly, doesn't listen to him and decides to marry him only. But soon, their respective families, too, come to know about the whole issue and start blaming one another. Mudit's father tries his best to convince him against marrying Sugandha, but he listens to no one and takes seven rounds of the holy fire in front of everyone.