Hancock, a UNESCO goodwill ambassador, is the force behind the creation of a world day of jazz on April 30 starting Monday.
The yearly event aims to encourage people around the world to break down barriers between them using music.
"International Jazz Day is the great metaphor for international harmony," Hancock told The Associated Press in an interview, before kicking off jazz day at UNESCO where it gets an early start.
Things were getting groovy behind the sober, concrete walls of the headquarters of the U.N. Educational, Scientific and Cultural Organization.
About 400 students from Paris music conservatories and schools were taking master classes from Hancock, Dee Dee Bridgewater or Ibrahim Maalouf. Workshops, films, lectures and performances by musicians from around the world preceded an evening concert with an array of artists, including South Africa's Hugh Masekela and French-born Manu Katche. And to show that jazz crosses musical borders as well as national ones, opera star Barbara Hendricks was taking part.
Hancock planned to cross the Atlantic to New Orleans, the birthplace of jazz, for a sunrise concert with jazz luminaries on Monday, then head to the United Nations in New York for a sunset jazz fest for diplomats that will be streamed live. Many countries, from Azerbaijan to India, plan activities of their own to celebrate jazz on Monday.
The Unites States formerly proposed to UNESCO the creation of International Jazz Day. U.S. Ambassador to UNESCO, David Killion said, "Jazz remains a powerful diplomatic tool for anyone to communicating across cultures, anyone committed to the freedom of expression and who appreciated the art of listening."
Jazz by its very nature is a bridge across cultures, says the 72-year-old Hancock, whose roots are in classical music. Jazz musicians feed off each other, exchanging, improvising, inspiring and creating together - and forbidding nothing.
"Jazz is very open and very willing to be inclusive instead of exclusive," Hancock said. "We all want to live in a jazz world where we all work together, improvise together, are not afraid of taking chances and expressing ourselves."
Jazz's roots among African-American slaves have long spoken to others with no voice but music, Hancock said.
"When a human being is oppressed, the natural tendency is to feel anger," he said. "Jazz is a response to oppression that is not bullets and blood. Jazz is the expression of harmony ... and at the same time of hope and freedom."