Shamna is popularly known as Poorna in Tamil industry. Vijay fans mention her as junior Asin. Shamna Kasim is more popular as a stage performer for filmy events. She made entry into films through Manju Poloru Penkutty.
Shamna is also seen in Janal Oram, the Tamil remake of Malayalam flick Ordinary. She also has Poomathe Ponnamma, under filming for the Malayalam. Aaru Sundarimaarude Katha was her last film in Malayalam.
In Chattakaari, Shamna played the role of a girl who falls in love with her friend's brother and later gets pregnant by him. He goes to US for a job. Her family keeps her away from his contacts and later comes to know that she is carrying. She is forced to get an abortion, but she denies and gives birth to a baby boy. In the climax, both re-unite with the help of a friend.