After completing a degree in architecture in New Delhi, he moved to London in 1955 where he lived until 1961.

Raj Rewal worked at Michel Ecochard's office in Paris before starting his practice in New Delhi in 1962.

Among his better known projects are the Hall of Nations (Hall 6) at the Pragati Maidan Exhibition Centre,[5] demolished in April 2017,[6] Asiad Village Complex, National Institute of Immunology (NII), New Delhi; the Parliament Library in New Delhi and NCBS (National Centre for Biological Sciences) campus at Bangalore.

He also designed an architectural college (SIUPA) in Rohtak and is head of members in academic council.

In 2018 his drawings and models were added to the New York Museum of Modern Art permanent collection, making him the first Indian architect represented.