The family immigrated to Belgium, where he started playing the piano at age 6 and initiated in jazz in his teens.

He returned as a teacher of jazz piano at the Brussels Royal Conservatory of Music, where he met Jacques Pelzer.

[4] In the 1990s, he worked with Flavio Boltro (trumpet) and Stefano Di Battista (saxophone) forming the jazz ensemble Éric Legnini Trio that caught attention in the 1990s.

He has played with fellow artists like Aldo Romano, Belmondo Quintet, John Ruocco, Félix Simtaine, Jeanfrançois Prins, Michel Hatzigeorgiou, Dré Pallemaerts, Emanuele Cisi, Toninho Horta, Philip Catherine, Serge Reggiani, Hein van de Geyn, Marcia Maria, Jacques Pelzer, André Ceccarelli, Éric Le Lann, Paco Sery and others.

Legnini had great admiration for the works of Phineas Newborn, dedicating the piece The Memphis Dude to him.