During a walk to the park Raghuraman (Prakash Raj) meets Sudhakar (Prithviraj Sukumaran) and tells him about his many experiences with his daughter Abhi (Trisha Krishnan). Raghuram is the loving husband of Anu (Aishwarya) and the worrisome as well as caring father of his only daughter Abhi. Together they all live a calm and content life in Ooty. Raghuram and Abhi become best friends. Over the years as Abhi grows up, Raghuraman has the joy of being a part of her everyday life. When Abhi gets accepted in a prestigious college in New Delhi, Raghuram is shocked. Although the thought of being separated from his daughter for two whole years is heartbreaking to him, Raghuram wearily accepts. As soon as Abhi returns from college, she tells her parents that she has fallen in love with a young man in Delhi. Her mother Anu is perfectly alright with the idea, but Raghuram is angry and scared. Anu later informs Raghuram that their future son-in-law will be arriving by plane and staying with them for a while. As soon as Raghuraman meets his future son-in-law, Joginder Singh (Ganesh Venkatraman) he is taken aback, because Joginder is a Sardarji! After many conflicts with Abhi and Anu, Raghuram finally realizes that Joginder is quite talented and self-sacrificing, more so when on one occasion the Prime Minister calls him for advice. Abhi and Joginder get married and leave for Delhi. Anu and Abhi get teary-eyed, but Raghuram stays calm. This is very surprising, because he was the man that had once cried on his daughter's first day to school. Raghuram tells Sudhakar that he still stays in touch with his daughter and often gets to see her. Sudhakar understands how Raghuram feels, because he has a baby daughter himself. The movie ends with a phone call from Abhi.
Abhiyum Naanum is inspired by the Hollywood flick, Father of the bride. Prakash Raj portrays the life journey of a father very effectively.