Mnatskan Petrosyan was born on February 16, 1956 in the town of Akhaltsikeh in Georgia.

Mr. Petrosyan graduated with a degree in economics from the Yerevan Institute of National Economy in 1980.

From 1973-1976 he was a worker in the Yerchimshin Trust. In 1980 he was appointed economist in the Elektrasark Industrial Complex. For the next three years he was the first secretary of LCYU Committee at the Yerevan Financial and Economic College. 1986 he was an instructor in the Division of Communist Youth Organizations in the LCYU Central Committee. In 1986 he was appointed head of the Registration and Statistics Subdivision. From 1986-1989 he was the deputy head of Communist Youth Organizations Division. From 1989-1990 he was the Department Administrator. From 1990-1994 he was the administrative officer in the Armenia Youth Union. From 1994-1997 he worked as a chief accountant in the Hayk Complex. From 1997-1998 he was the manager of Edjhmiztsin branch of Hayeconombank. For the next two years he was the office manager at Hayagrobank and from 2000-2002 he was deputy director. From 2002-2003 he was the deputy director of Arsoil Armenian Enterprise CJSC.

On December 11, 2003 he was elected to the NA from the proportional list of the United Labor Party.Till June 2,2006 he was the Deputy Chair of the NA Standing Committee on Social, Health Care and Environmental Protection Affairs. From June 2, 2006 he is the Chairman of the NA Standing Committee on Social, Health Care and Environmental Protection Affairs.
 

He is a member of both the United Labor Party Faction and party.

Mr. Petrosyan is married and has two children.