Nicolăescu was born in Grădiștea village, Comana Commune, Giurgiu County. Between 1976 and 1985, he was successively technologist, sales clerk, commodities economist and economist at various Bucharest hotels, including Athénée Palace. He took a hiatus in 1976–1977 in order to fulfill his mandatory military service, and in 1982 graduated from the Commerce Faculty of the Bucharest Academy of Economic Studies (ASE), earning a doctorate in Economics from the same institution in 2007. From 1985 to 1987, Nicolăescu was a computer analyst dealing with supplies at the special equipment factory of the Ministry of Industry and Resources. From 1987 to 1990, he was an economist in the supplies division of the same factory. Following the fall of the Communist regime, from 1990 to 1998, he worked at the military equipment company Ratmil, successively as head of supplies, supplies economist, head of budget and economic analysis, economic director and general director. From 1998 to 1999, he was economic director at a construction firm. From 1999 to 2000, he was adjunct secretary general at the Ministry of Public Finance. In 2000, he was head of the interim national committee on real property values, but resigned. In 2000–2001, he was assistant professor at Spiru Haret University, holding the same title at ASE from 2001 to 2002. He has several publications in his field.