Maiman, the son of an electrical engineer, was born in Los Angeles, California, and graduated in engineering physics from the University of Colorado in 1949. He gained his PhD from Stanford University in 1955, following which he joined the Hughes Research Laboratories, Miami.

Maiman was especially interested in the maser, which had been developed independently by Charles Townes in America and Nikolai Basov and Aleksandr Prokhorov in the USSR in 1955. It was realized that the principles by which the maser produced microwaves at selected well-defined wavelengths could be extended to emissions at the shorter visible wavelengths. In 1960, at the Hughes Research Laboratory, Maiman designed and operated the first instrument to achieve this, now known as the laser (light amplification by stimulated emission of radiation). He used a ruby cylinder with mirror-coated ends as a resonant cavity, and succeeded in converting flashes of white (incoherent) light into a pulsed beam of monochromatic coherent light. Such a beam can travel long distances with little dispersion and can concentrate optical energy on a small spot. The first continuous (as opposed to pulsed) laser was made by Ali Javan (1926–2016) and his colleagues at the Bell Telephone Laboratories in 1961. The laser has since been developed in many forms as a research and engineering tool.

Maiman founded his own company, Korad Corporation, in 1962, which became the leading developer and manufacturer of high-power lasers. He founded Maiman Associates in 1968, acting as a consultant on lasers and optics, and cofounded the Laser Video Corporation in 1972. In 1977 he joined TRW Electronics of California as assistant for advanced technology.