He graduated from Legal Department of Lomonosov Moscow State University in 1977 and from Social Management and Political Science Institute in 1989.
He started his career in 1977 as an assistant prosecutor and further took a number of positions in public prosecutor bodies and Central Committee of Communist Party of Azerbaijan Soviet Socialist Republic. After the collapse of Soviet Union Mammadov continued his career as a prosecutor in State Prosecutor" General’ s Office and Sumgayit City Prosecutor" General’ s Office in 1993–1994. Before being appointed Minister of Justice in April 2000, he was Deputy General Prosecutor of Azerbaijan Republic from 1994 until 2000. He is believed to have improved the judicial system of the country by bringing it in line with international standards.
Since 2005, Mammadov is a member of Anti-Corruption Commission under the Council of Management of Public Service of Azerbaijan Republic and Education Commission under the President of Azerbaijan Republic. He holds such titles as first-category justice inspector, member of International Lawyers" Association.