[5] Sen was first recognised as a model when she performed in Falguni Pathak's music video Yaad Piya Ki Aane Lagi at the age of seventeen in 1998.

Sen has worked as an activist and appeared in an AIDS awareness music video with the aim of dispelling popular myths about the disease.

[8][9] Riya and the second female lead of the film were replaced by aspirant actresses Sonali Joshi and Jaya Seal in Xcuse Me.

[10] Her next success was Jhankaar Beats, comedy revolving around the music of legendary composer R D Burman, which saw her playing a small and glamorous role[11] alongside Shayan Munshi, Juhi Chawla, Rahul Bose, Rinke Khanna and Sanjay Suri.

Produced by Pritish Nandy, publishing director of The Times of India,[12] the film was made on a budget of Rs.

25 million (US$525,000),[12] marking the sixth in a row of small to medium budget films made by Pritish Nandy Communications (PNC).

[22][23] Besides this, she performed another item number in James (2005) on director-producer Ram Gopal Varma's behest, who has a history of casting aspirant actress-models like Sameera Reddy, Isha Koppikar and Koena Mitra in similar roles.

[citation needed] Her first English language movie was It Was Raining That Night, a remake of the Bengali film Hei Brishtir Raat, scripted by Sudeshna Roy and directed by Mahesh Manjrekar.

[30][31] She played the role of Bhama in the film, a village girl who is lured by Digambaran, the evil magician portrayed by Manoj K. Jayan.

In a song-and-dance sequence showing Digambaran turning Bhama into a medium for demonic rituals, the choreographer Aparna Sindoor made abundant use of Kathakali movements.

[32] The use of Kathakali has been a high point in the resurgence of the classical dance form in other major Indian films as well,[33] including Shaji Karun's Vanaprastham (1999) and Adoor Gopalakrishnan's Kalamandalam Ramankutty Nair (2005).

She participated in fashion shows along with her elder sister, Raima Sen.[45] Besides modelling, Riya has ventured into the advertisement world as well.

A high point of her modelling career came in 2006, when she became the soft drink, Limca's brand ambassador, replacing Deepika Padukone.

[46][47] Her other notable assignments include Colgate, Dabur Vatika, Reliance Industries, Cadbury Dairy Milk Chocolate, and Nirma.

[60] The sisters are credited on-screen under their mother's maiden name, although their official papers carry the surname Dev Varma.

She went on to studying philosophy in a Bengali uccha madhyamik school Rani Birla Girls' College (a University of Calcutta affiliate).

Riya also did a course at the University of Arts in London in ‘branding' and a cooking course in Thailand at the blue elephant culinary school.

1[citation needed] and sharing on-screen kisses with co-stars Ashmit Patel in Silsiilay and Sharman Joshi in Style, respectively.

Such performances garnered negative attention because of the relatively conservative outlook of Indian cinema at that time and her own statements about such practices.