Membership criteria vary among institutions- joined or willing to join AAOIFI. However, founding members stand apart, being the Islamic financial institutions which are signatories to the agreement establishing the organization in 1989. Those members are: the Islamic Development Bank (Saudi Arabia) www.isdb.org, Al Baraka Banking Group- ABG- (Bahrain) www.abg.bh, Dar Al Mal Al Islami (Switzerland), Al Rajhi Banking and Investment Corporation (Saudi Arabia), Kuwait Finance House (Kuwait) www.kfh.com and Bukhari Capital (Malaysia).

Associate members are those Islamic financial institutions and companies that comply with Islamic Shari'a precepts and principles in their operations and transactions.  In addition, Islamic Fiqh academies and institutions that have corporate entities have their say in this class.

AAOIFI's membership base is not limited to founding and associate members. Members representing regulatory and supervisory authorities -  central banks, monetary agencies, and suchlike- form a distinct category, playing vital role by supervising Islamic financial institutions and their contribution towards the economy at large.

The last class of membership is observer members. Those members include organizations and associations responsible for regulating the accounting and auditing profession and/or those responsible for preparing accounting and auditing standards. Practicing certified accounting and auditing firms that have interest in the accounting and auditing practices of Islamic financial institutions are among observers as well.  The list goes further by admitting financial institutions engaged in financial activities of Islamic financial institutions (Islamic banking windows, for instance). Users of financial statements of Islamic financial institutions- both individuals and corporate- belong to the category, as well, and their observing role can't be underestimated.

Supporting members, finally, comprise of users of financial statements of Islamic financial institutions- individuals and corporate, in addition to local and international financial institutions that already have or intend to have relations with Islamic financial institutions' products.