[1] Siddiqi was Chairman of the Religious Affairs Committee of the Muslim Students Association in the United States and Canada, and he also served as Director of the Islamic Center of Washington, D.C. Siddiqi served two terms (1997–2001) as president of the Islamic Society of North America with headquarters in Indiana.
[2][3] He conducted a weekly religious radio program from Pasadena from 1982 until 2004, and has contributed articles to Islamic and academic journals, encyclopedias, and other publications.
He writes a weekly column for Pakistan Link in Los Angeles on the issues of Islamic law and social problems.
Siddiqi is the current President of the Academy of Judaic-Christian and Islamic Studies at the University of California in Los Angeles (UCLA).
In August 2006, as part of a special feature called "The West 100", the Los Angeles Times recognized Siddiqi as one of the top 100 most powerful people in Southern California with the following description: "Siddiqi, whose mosque is among the largest in North America, is the religious leader of thousands of Southern California Muslims at a time when xenophobia is running high… he has been a leader in driving home the point that Muslims in the U.S, are peace-loving.