Inspite of his professional qualification in Hotel management, his heart was more inclined towards acting but was dissuaded by Subhash Ghai due to the hardships involved in succeeding as an actor in Bollywood. His persistence paid reward dividend when he got to play the lead role in Jaan Tere Naam (1992) which was a commercial success. Then he starred with Aditya Pancholi and Kishori Shahane in Bomb Blast (1993).
Ronit received a call from Balaji Telefilms to offer him a part in the television serial Kammal. Due to the lack of any appealing movie offers, he accepted the offer. Before Kammal got started, Balaji Telefilms also offered Ronit an 8-week cameo in Kasautii Zindagii Kay as Rishabh Bajaj, a ruthless yet suave middle-aged business tycoon. Ronit's impressive performance as Mr. Bajaj made him popular and landed him in Balaji Telefilms' Kyunki Saas Bhi Kabhi Bahu Thi as Mihir Virani, replacing Amar Upadhyay. Then it was simply no looking back. He became eventually famous for his portrayal of Dharamraj Mahiyavanshi (in Bandini). He further matured as an actor when he gave good performances as KD Pathak (in Adaalat), Rishabh Bajaj (in Kasautii Zindagii Kay), Mihir Virani (in Kyunki Saas Bhi Kabhi Bahu Thi) and Neil Khanna (in Itna Karo Na Mujhe Pyar).
In the meantime, he married actress and model Neelam Singh. Ronit got blessed with two children - a daughter and one son. In May 2005, his and Neelam's first child, daughter Aador, was born. In October 2007, their son, Agasthya Bose Roy was born. Though he also has another daughter, Ona (from his previous marriage) who was born in 1991, and currently resides in the US.
After his success on TV, Ronit featured in more Bollywood movies in supporting roles. In 2010, he starred in the critically acclaimed film Udaan; his work was much praised and won him many best supporting actor awards. Udaan brought Ronit back to the movie scene. He next starred in films such as Anurag Kashyap's That Girl in Yellow Boots, Karan Johar's Student of the Year, Deepa Mehta's Midnight's Children, Sanjay Gupta's Shootout at Wadala (produced by Ekta Kapoor), and Anurag Kashyap's Ugly. More recently, he appeared in the Akshay Kumar starrer BOSS and the Arjun Kapoor starrer 2 States in which his performance received much appreciation.
His acting career got a shot in the arm when he received Filmfare Award for Best Supporting Actor for his role as Bhairav Singh in Udaan in 2010. Again in 2010, he got nominated for Filmfare Award for Best Supporting Actor for his role as Vikram Malhotra in 2 States. This was followed by Star Screen Award for Best Actor in a Negative Role as Billu Pehelwannin Guddu Rangeela in 2015. Then there was simply no looking back. This was the time when he got recognized as a villain. This recognition followed with big banners offering him meaty roles as the bad guy. Then it was the turn of Kaabil, Sarkar 3 and Lucknow Central apart from a number of other Box Office failures.
His upcoming movies include Jai Lava Kusa (2017) in Telugu and another untitled project by Aanand L. Rai of Tanu Weds Manu fame.
It's basically with Kaabil that he founded his ilk and has become a preferred choice to play as the villain. Though his journey has been very very difficult, he has been able to carve a niche. As a versatile actor with tremendous acting experience, his best is yet to come and he certainly has left his footprints in Bollywood.