Belzberg received a B.A. in 1991 from the University of Colorado, Boulder and an M.A. in 1997 from the School of International and Public Affairs, Columbia University. She received the Columbia University School of Journalism’s John M. Patterson Enterprise Award in 1997 for her documentary short “A Master Violinist”, about a Chinese political refugee.
With assistance from the Soros Documentary Fund (now the Sundance Documentary Fund), Belzberg made her first feature film Children Underground, a documentary about five homeless street children who live in the subway system of Bucharest, Romania. The film won the Special Jury Prize at the Sundance Film Festival (2001), and received the Best Documentary Film Award from the International Documentary Association (2001). Children Underground was also nominated for a 2001 Academy Award and was one of the first recipients of the IFP Anthony Radziwill Documentary Prize. 
Her 2005 documentary Gymnast studied three American female gymnasts preparing for the Olympic Games.
In 2005, she received the MacArthur “Genius” award. She lives in New York City, where she has been a frequent guest lecturer on urban reporting and documentary filmmaking at the Columbia School of Journalism, and has also taught at NYU. 
Belzberg’s most recent documentary, The Recruiter (originally titled An American Soldier), premiered at the 2008 Sundance Film Festival. It portrays a top U.S. army recruiter and his relationship with four of his recruits as they complete high school and go through basic training.