Kavya Madhavan first appeared as a child actor in Kamal's film Pookkalam Varavayi (1991) at the age of seven. Subsequently, she was offered parts in other projects such as Pavam IA Ivachan (1994), Parassala Pachan Payyannur Paramu (1994) by P.Venu and Azhakiya Ravanan (1996), directed by Kamal.

She was offered the female lead in Chandranudikkunna Dikhil, also starring Dileep, in 1999.

After the success of Chandranudikkunna Dikhil, Kavya Madhvan and Dileep became a popular pairing in Malayalam cinema, and they worked together in 18 movies. Some of their movies are Thenkasipattanam (2000), Darling Darling (2000), Meesa Madhavan (2002) which was one of biggest grosser of the year and was directed by Lal Jose, Mizhi Randilum (2003) in which she played a double role, Sadanandante Samayam (2003), Thilakkam (2003) directed by Jayaraj, Runway (2004) directed by Joshiy, Kochi Rajavu (2005), Lion (2006) again directed by Joshiy, Chakkara Muthu (2006), Inspector Garud (2007), Paappi Appacha (2010), Vellaripravinte Changathi (2011) and Pinneyum (2016). Most of their movies were in the romantic comedy genre.

Though she had many offers from Tamil cinema, she was very reluctant to act due to her busy schedule in Malayalam. Her first was Kasi (2001) which was the remake of Vinayans Vasanthiyum Lakshmiyum Pinne Njaanum. She went on to act in En Mana Vaanil and Sadhu Miranda and enjoyed moderate success.

She got critical acclaim for her performance of the role of Ganga in Perumazhakkalam for which she won 2004 Kerala State Film Award for Best Actress and for the role of Ashwati in Gaddama where she played a housemaid working in Saudi Arabia. The movie was based on a feature by K. U. Iqbal, published in Bhashaposhini. The movie was directed by her mentor Kamal, and she got her second Kerala State Film Award for Best Actress for 2011. She won the 2011 Kerala Film Critics Awards for Best Actress, Amrita-FEFKA Film Awards for Best Actress, Best Actress-Malayalam cinema in 59th Filmfare Awards South and Best Actress in Thikkurissy Foundation Awards. She was nominated in National film award for Best Actress but lost out in the final round. She was part of big grossers like Christian Brothers and China Town in 2011 and was selected as Top Star (Female) 2011 in Malayalam.

Kavya married Nishal Chandra on 9 February 2009, after which she moved to Kuwait. However, she returned home in June the same year and filed for divorce on 24 July 2010. Both Kavya and Nishal appeared before the court on 25 May 2011 and expressed their willingness for a mutual divorce. The divorce was granted on 30 May 2011. After long speculations regarding her romantic relationship with Malayalam actor Dileep and despite both denying it on several occasions, she married him on 25 November 2016 at Vedanta Hotel, Kochi. Many famous from tinseltown attended the wedding including Mammootty, Menaka Suresh, Jomol, Srinda, Meera Jasmine, Jayaram.

In 2012, Kavya released a Malayalam album titled Kavyadalangal which was composed by Twinz Tunes and Kavya. She was featured in the video under the direction of Aneesh Upasana.

In April 2013, Mathrubhumi Books published a collection of memoirs written by Kavya, titled Kathayil Alpam Kavyam which gives a glimpse into her childhood memories and the experiences of her school days and in the film industry. The book was released by Writers Subhash Chandran and Deedi Damodaran at a function held in K. P. Kesava Menon Hall in Kozhikode on 11 April.