Graduated from Magnitogorsk State Technical University in 2001 with a degree in economics and management in the metals industry, and in 2005 from the Russian Government Finance Academy in financial management.
Head of the Planning and Economics at Magnitogorskmezhraigas, Chief Economist at Magnitogorsk Energy Company, 1999 — 2003. From 2003 to 2007 he was CEO of LLC Upper Urals Distilling Company Yantar. From 2007 to 2014 Sergei Nenashev served as director of LLC Magnitogorsk Service Centre. From 2015 to 2016, Director for Labor Protection, Industrial Safety and Ecology of OJSC MMK. From 2017 to August 2021 — Commercial Director of PJSC MMK. Since August 2021 — Director for Strategy and Development of PJSC MMK.