Born on January, 1, 1948 in Malin, Zhitomir region (Ukraine).
After finishing secondary school (Krasny Luk, Lugansk region) entered Lugansk Railroad technical school, department of transport building. After finishing the technical school worked as a master of metallurgical and coal industries.
After service in the Army studied at Kiev engineer-building institute (graduated in 1970), qualification - industrial and public building.
In 1983 - graduated from the Academy of people's economy, in 1988 - from Academy of economy (Germany).
From 1970 to 1980 I.I.Mazur was chief engineer and manager of the trust "Megiongazstroi", Nizhnevartovsk, Tumen region.
In 1980 he was appointed head of 'Soyuztransprogress', in 1981 - head of "Glavtruboprovodstroi" - the largest company in the European part of the former USSR specializing on construction of oil pipelines.
From 1985 to 1991 - Mazur worked as a deputy Minister of USSR construction.
Later was appointed vice-president of the State company "Neftegazstroi" and "Rosneftegazstroi".
In 1996 - was elected Chairman of board of directors of JSC "Rosneftegazstroi", from 1998 to the present time - Chairman of JSC "Rosneftegazprom" board.
In 1981 I.I.Mazur defended Candidate thesis on the problems of nature-saving building in the North.
In 1991 - defended Doctor thesis on the problem of stability and ecological safety of oil and gas objects.
I.I.Mazur was pioneer of the new scientific branch - "Engineering Ecology", has author licences on 18 inventions.