An invaluable expert in his field and an exemplary public servant who has dedicated his career to serving the Canadian public, Fellegi has been honored with numerous awards and accolades, including six honorary doctorates, the Order of Canada, the Order of Merit of the Hungarian Republic, Career Achievement Award of the Canadian Policy Research Initiative, and the Outstanding Achievement Award of the Public Service of Canada.

Born in Szeged, Hungary, Fellegi was working his way to complete mathematical studies at the Eötvös Loránd University when the Hungarian Uprising was crushed in 1956.

When Fellegi was 21 years old, his mother arranged for a sympathetic physician to label her son a tuberculosis patient so that he could travel to the border area near Austria, ostensibly to receive treatment.

In 1957, Fellegi completed his studies with night courses at Carleton University, in spite of being a new refugee without access to his Bachelor of Science transcripts.

In 1957, Fellegi was hired as a statistician at Statistics Canada, despite having not yet mastered English or French or being a Canadian citizen.

As an Assistant Chief Statistician, he took leave without pay in 1978 to work for the United States Commission on the Reorganization of the US Statistical System as established by President Jimmy Carter.

As such, he played a key role in coordinating the (overlapping) mandates of the OECD Statistics Committee and the Conference of European Statisticians.

He contributed to a number of international statistical projects, including work on the United States Census through the National Academy of Sciences.