Leon Harris Charney was born to a Jewish family in Bayonne, New Jersey, to Morris, a sewing supplies salesman who died at a young age when his son was young, and Sara Charney. He grew up poor. He attended Jewish day schools, worked as a counselor at Camp Winsokee, graduated from Yeshiva University in 1960, and from Brooklyn Law School in 1964. He paid for his education in part by singing in synagogues, and by selling sewing machines door-to-door.

He became a member of the bar in 1965, and with $200 in the bank started his own law firm representing sports and show-business personalities, including Jackie Mason and Sammy Davis Jr. As a young attorney, he was also a fierce advocate for the passage of the Good Samaritan Law after witnessing a man die in public when doctors refused to intervene out of fear of being sued.

In 1986 Charney went to Tunisia to meet with Yasser Arafat in the hope of a possible peaceful resolution of the Israeli–Palestinian conflict.

In 2003, Charney donated $10 million to NYU Langone Medical Center for a new cardiac wing of the hospital. He is also the major benefactor of the University of Haifa’s Leon H. Charney School of Marine Sciences, for which he reportedly donated more than $10 million in 2007.

Charney hosted a national weekly TV talk show Leon Charney Report which dealt with local New York politics, foreign affairs and the Middle East, social issues and popular culture. Over its 25 years of broadcasting, the show featured numerous prominent guests including Ed Koch, Rudy Giuliani, David Dinkins, Shimon Peres, Yitzhak Rabin, and Ehud Barak. Although his show was seen weekly on WNYE-TV for years, in later years it gained ground after Arnie Mazer became the Senior Producer and when the station became NYC Media in 2005, after New York City Mayor Michael Bloomberg enabled his top media executive, Arick Wierson, to merge the stations with the existing nyctv cable channels. Via nyctv, The Charney Report began podcasting its audio version on NPR and the audio component began to be nationally syndicated as radio programming.

In 2009, Charney was a featured interviewee in a Harry Hunkele documentary film starring former U.S. President Jimmy Carter entitled Back Door Channels: The Price of Peace which is opening in the heart of the Arab world in Abu Dhabi in October 2010 at the Abu Dhabi Film Festival, also known as the Middle East International Film Festival. The film was the source of much buzz in the diplomatic sphere, as it is rumored that many never before revealed aspects of the original peace process were unveiled, some of which paint a less than rosy picture of American diplomatic efforts at the time. It has only been verified that the movie has been shown once, in Monte Carlo, due to a special request made by Albert II, Prince of Monaco, the President of the Festival, to Arick Wierson, the film’s executive producer.

In 2014, Charney received an Emmy Award for the television version of the documentary.

Charney received honorary doctorates for his work in peacemaking including those from the University of Haifa, Yeshiva University, Florida Atlantic University, and the University of Indianapolis. Charney also received awards from a number of institutions and city governments including the City of New York, City of Bayonne, and the Foundation for Ethnic Understanding. In 2016, the Diplomacy Program at Florida Atlantic University was named in honor of Mr. Charney. The Leon Charney Diplomacy Program, which trains undergraduate students in the art of negotiation and conflict resolution, placed first overall in the National Model United Nations competition in Washington, D.C.