The National Endowment for the Humanities, an independent federal agency and the foremost sponsor of educational and research projects in the field of humanities, has recognized the need for and significance of the Encyclopædia Iranica, which it has classified and supported as a “major project” since 1979 — an impressive exception both in terms of the duration of sponsorship and the amount of support accorded to research-tool projects.

The American Council of Learned Societies endorses the Encyclopædia Iranica. Professor Stanley N. Katz, former ACLS President, wrote to the Editor: "It is an honor for the ACLS to have even this remote connection to such a distinguished academic undertaking, and I congratulate you on this success and wish you the best of luck in the continued excellence of the Encyclopaedia."

In June 1997, following the sponsorship of The American Council of Learned Societies, the Union Academique Internationale voted unanimously to extend its patronage to the Encyclopædia Iranica project.

In 1990, the Getty Grant Program, well-known for its sponsorship of art history and archeology studies, also recognized the particular contribution of Encyclopædia Iranica in these fields by allocating a substantial grant for a 3-year period. 

Many foundations, organizations and individuals with an interest in Iranian culture have supported the Encyclopædia Iranica. Khosrow Eghbal, a former chairman of the Encyclopædia Iranica Foundation, assigned $2 million for the Encyclopædia in his will. Mahmoud Khayami, now the Honorary Chairman of the Foundation, and Mr. and Mrs. Khosrow B. Semnani have made considerable contributions to the Encyclopædia. Dr. Akbar Ghahary, Dr. Abtin Sassanfar, Mrs. Sadigheh Rastegar, all trustees of the Encyclopædia Iranica Foundation, Iran Heritage Foundation, Soudavar Memorial Foundation, and many other supporters have helped finance the progress of the project.

The Encyclopaedia Iranica Newsletter, formerly published print twice per year, has been replaced by an e-mail newsletter, which regularly acknowledges donor contributions. The Foundation also honors extraordinary commitments by dedicating a volume of the Encyclopaedia Iranica to each donor who gives $500,000 or more, a single tribute among the many privileges accorded to top-tier supporters.