Devayani's was born Mumbai, Maharashtra to Jayadev and Lakshmi. She has two brothers, Mayur Jaidev and Nakul. She studied Bachelor of Commerce in National College at the Mumbai University. She married Rajakumaran on 9 April 2001. Devayani first met her husband when she was acting in Suryavamsham, when Rajakumaran was assistant director. She starred in Nee Varuvai Ena, Rajakumaran's debut film. A daughter was born to the couple in 2006 and a daughter in 2008.
Devyani began her career as 'Sushma' in the Hindi film Koyal, which was later cancelled during its production stage. She appeared in a Bengali film Shaat Ponchomi. She also acted in a Marathi film before debuting and rising to fame in Tamil cinema. Her earliest films were released in the early and middle 90's including Kadhal Kottai. From 1996 to 2000 Devyani acted as heroine in over 35 films and acted alongside all the top actors. She moved into supporting roles in Thenali though she still acted commercially until 2004-2005. Devayani considers actress Roja Selvamani as her mentor and close friend in film industry. Having helped Devayani to improve her hair styles in movies, Roja had also been her moral support during her marriage with Rajakumaran. Devayani began acting in the teleserial Break Kolangal as Abhinaya which has had over 1500 episodes on Sun Television.