Leal received his B.S. degree from the University of Washington in 1965, M.S. degree from the Stanford University in 1968, and Ph.D. degree from the Stanford University in 1969; all in chemical engineering. His Ph.D. thesis advisor was Andreas Acrivos.

Leal started his academic career in 1970 as an Assistant Professor in chemical engineering at California Institute of Technology. He became Full Professor in 1978. During 1986-1989, he was Chevron Distinguished Professor of Chemical Engineering. In 1989, Leal joined University of California, Santa Barbara as Professor and Chair in the Department of Chemical Engineering. He is currently the Warren and Katharine Schlinger Professor of Chemical Engineering at UCSB.

Leal's research covers a wide range of topics in fluid dynamics, including dynamics of complex fluids, such as polymeric liquids, emulsions, polymer blends, and liquid crystalline polymers. He also works on large-scale computer simulation of complex fluid flows. Leal and his coworkers made pioneering contribution to study of drop deformation under different flow conditions. They have developed a scheme based on a finite difference approximation of the equations of motion, applied on a boundary-fitted orthogonal curvilinear coordinate system, inside and outside the drop. Leal has published more than 250 papers on fluid dynamics. He has directed 55 Ph.D. thesis in various topics in fluid dynamics.