Nair was a still photographer at the start of his career and his friendship with directors like Ramu Karyat and P Bhaskaran made him enter the cine world. He made his debut with the the black-and-white classic Neelakkuyil. Not only did the movie do well among the audience it went on to become a path-breaking movie in the history of Malayalam cinema.
Parameswaran Nair will perhaps be most remembered for getting Malayalam cinema out of the clutches of studio shoots to realistic outdoor locations. He gave his directors a free hand and till date is regarded as one of the most respected producers in the Malayalam industry. His Sobhana Studio delivered many hits including Murappennu, Ninamaninja Kalpadukal and Kallichellamma.
Nair took a lot of interest in turning literary works into motion picture and many of the literary works of renowned author like M T Vasudevan Nair was made into cinema. Sources close to him said Nair never believed in making movies for the sake of money and believed the primary job of a movie should be to transform the society.