She returned to Romania in 1991, after the fall of the Communist regime, singing for the first time on a stage in her native country, in a Concert at the Romanian Atheneum in Bucharest. As some 10,000 tickets were purchased, Nicolesco gave three consecutive performances. She created the Romanian Atheneum International Foundation and donated in 1994 a Steinway grand concert piano. In 1995, Mariana Nicolesco initiated the Hariclea Darclée International Voice Competition and Festival. In the years between an edition of the Contest and the next, she offers Master Classes to the young artists. She obtained for the Darclée events the High UNESCO Patronage. In 2003, she created the Romanian National Festival and Song Competition and presented for the International George Enescu Year, proclaimed by UNESCO (2005), in world première the composer's complete songs in Japan, at Aichi World Exhibition as well as in Nagoya and Tokyo, in Prague, Paris, Rome and New York City. In 2014 she is a Member of the Jury of China International Vocal Competition with 430 competitors from 41 countries.