In 1978, while still an understudy, Hussain laid out the All Pakistan Mohajir Understudies Association (APMSO) to advocate for the privileges of the Mohajir people group - Urdu-talking workers from India. This development established the groundwork for the development of the Mohajir Qaumi Development in 1984, which was later rebranded as the Muttahida Qaumi Development (MQM) in 1997 to mirror a more extensive political plan. Under Hussain's administration, MQM arose as a huge political power, particularly in metropolitan Sindh, resolving issues of ethnic portrayal and upholding for the privileges of minimized networks.
Confronting political and lawful difficulties, Hussain looked for shelter in the Unified Realm in 1992, where he has lived since. In spite of his purposeful exile, he kept on affecting Pakistani governmental issues, frequently tending to his allies by means of telephonic talks. Throughout the long term, Hussain has been a dubious figure, confronting different charges and judicial procedures. In 2019, he was captured in London concerning a 2016 discourse yet was vindicated in 2022. All through his vocation, Hussain has been a vocal pundit of Pakistan's tactical foundation and has reliably pushed for the freedoms and acknowledgment of the Mohajir people group.