Hassan's professional music career started at the age of fifteen; she met film director Feroz Khan at a party in the United Kingdom, who later requested that she audition with Biddu, a London-based Indian music composer, for his film "Qurbani". Biddu then signed her up for "Aap Jaisa Koi", a song he composed for the film. The song turned to be a huge success in India, and Hassan quickly gained recognition and acclaim. In 1981, Hassan won the Filmfare Award for Best Female Playback for the song, becoming the youngest to win at age 15 as well as being the first Pakistani to win the award.Hassan promptly collaborated with Biddu on numerous other projects; in 1981, she became the first playback singer to release an album. Her first album was "Disco Deewane". The album broke sales records in Pakistan and India and even topped the charts in the West Indies, Latin America and Russia, becoming an international success. The album became a mega-hit and Hassan became an established pop singer in Pakistan; the album also featured vocals by her brother Zohaib Hassan. Nazia and Zoheb were signed by EMI Group and were the first South Asian singers to be signed by an international music company. At the height of "Disco Deewane" fever, she frequently drew large crowds, such as 50,000 to 100,000 people greeting her at Calcutta Airport.