Leonidas Ioannidis was born in Athens. From 1982 he started trumpet lessons at the Athens Conservatory. He also studied piano, percussion, saxophone, flute, trombone and music theory.

He started playing professionally since 1992. He has collaborated with many of the most popular Greek artists, as well as artists from abroad.

In 2021, together with the pianist Giorgos Mikros, he created the Round Midnight Project, which recorded the album "Nocturnes" with arrangements of compositions by Mikis Theodorakis.

He is a member of Sketches of Grey, with whom he released the album Session 1 in 2022.