Riteish played the role of Karan Pandey in Sangeeth Sivan's comedy thriller Kyaa Kool Hai Hum in 2005, also starring Tusshar Kapoor in the lead role. Actresses Isha Koppikar and Neha Dhupia played the female leads in the movie. Kyaa Kool Hai Hum was a commercial success, despite being criticised for its adult humour.
Riteish was also seen in Bluffmaster!, starring Abhishek Bachchan and Priyanka Chopra, the same year.
He was also seen in Mr Ya Miss, a multi-starrer with Antara Mali, Aftab Shivdasani and Divya Dutta in pivotal roles.