Khalili started his business career trading in art before moving into property development and commodities. He began collecting art in New York City in the 1970s, keeping the best pieces for his own collection. In the mid 1970s he moved to London and began to frequent its auction houses, establishing his own gallery in Mayfair between 1978 and 1980. Khalili initially traded in Persian lacquerware, later writing his doctoral thesis on the subject. In 1978, the price of Islamic art fell substantially. The Iranian Revolution brought more items onto the market as rich families sold their art and during the subsequent Iran-Iraq War there was little interest in collecting art in that region. Khalili took the opportunity to expand his collection, acquiring works that would be valued much more highly with the later growth of international interest in Islamic art.