As with most film stars, speculation surrounded Nimmi's personal life. Because of her successful on screen association with Dilip Kumar, baseless rumours and stories were printed of an off screen liaison between the two. This was entirely false, and was strenuously denied by both Nimmi and Dilip Kumar, who at the time was in a relationship with Nimmi's contemporary, Madhubala.
Nimmi herself fell in love with screen writer S. Ali Raza, who wrote the dialogues for her films Barsaat (1949), Aan (1952) and Amar (1954). S. Ali Raza was the nephew of famous Bollywood story, dialogue and screenplay writer Aghajani Kashmeri (aka Kashmmiri and Agha Jani), who trained Ali Raza and introduced him to Bollywood. Both were from Lucknow. She married Ali Raza and settled down in Mumbai in the mid-1960s when she retired after her last film Akashdeep (1965) opposite Ashok Kumar. Nimmi and her husband never had any children. She remained happily married for 42 years until S. Ali Raza died on 1 November 2007 of heart failure at the age of 85, leaving Nimmi a widow. She now lives alone in her sea-facing Juhu Beach apartment in Mumbai. In June 1991 Nimmi was in the spotlight again when a non-published, non-sourced news source claimed the Hindi actress Kimi Katkar is Nimmi's daughter, but failed to offer any evidence, other than some alleged "face resemblance".
Unlike many vintage stars, Nimmi is not in seclusion and is often seen attending industry functions and events, with former colleagues such as Dilip Kumar. She is also often seen entertaining guests at the NSCI (National Sports Club of India) in Bombay, close by to her earlier home in the Worli area of Mumbai.
With Madhubala, Nargis, Nutan, Meena Kumari, Geeta Bali and Suraiya all deceased, Nimmi is widely considered to be one of the last remaining great leading ladies of the 1950s.