Mizsei has held senior positions at many Hungarian and international organizations.

In 2019, he joined the European Union High Level Advisers' Mission to help the Moldovan government to strengthen its reintegration policy.

From 1992 to 1995, Mizsei served as vice president for economic programs at the EastWest Institute in New York City.

Later he worked as chairman at the Hungarian Export-Import Bank Ltd. and Hungarian Export Credit Insurance Ltd. From 1997 till 2001, Mizsei was director of AIG Global Investment Group for Central and Eastern Europe.

[3][4] In 2019, he joined the European Union High Level Advisers' Mission to help the Moldovan government to strengthen its reintegration policy.