In 1987 Gelbart was elected a Fellow of the American Physical Society "for his many contributions to the light scattering and phase transition properties of simple fluids, liquid crystals, and surfactant solutions". He received the 1991 Lennard-Jones Prize of the British Royal Society of Chemistry, a 1998 Guggenheim Fellowship, the 2001 Liquids Prize of the American Chemical Society, election to the American Academy of Arts and Sciences in 2009, and endowed lectureships over the past 25 years at the Curie Institute (Paris), the University of Leeds (England), Case Western Reserve University, Cornell University, Carnegie Mellon University, the University of Pittsburgh, and the University of Texas at Austin. At UCLA he won the 1996 University Distinguished Teaching Award, served as Chair of the Department of Chemistry and Biochemistry (2000-2004), and was awarded the Glenn T. Seaborg Medal in 2017. In 2016, his 70th birthday was honored by an international symposium on "Self Assembly, from Atoms to Life" at the Meso-American Center for Theoretical Physics, and by a "festschrift" issue of the Journal of Physical Chemistry B.