Porter, who was born at Yarmouth in Nova Scotia, Canada, studied biology at Acadia University and Harvard, receiving his PhD in 1938. After working at the Rockefeller Institute (1939–61) he held chairs of biology, first at Harvard (1961–70) and thereafter at the University of Colorado.

While working with Albert Claude at the Rockefeller Institute, Porter studied the endoplasmic reticulum, a network of membranes within cells. More significant was his study of its equivalent form in muscle fibers, the sarcoplasmic reticulum. Although this had first been discussed by E. Veratti in 1902, it required the development of the electron microscope to permit Porter to describe, in the 1950s, its pervasive character as a network of extremely fine channels enclosing each myofibril. He went on to propose that it served to coordinate and harmonize the complex response of the contractions of millions of fibers.

The actual mechanism of contraction was initiated by the release of calcium ions into the fluid surrounding the muscle fibers. The source of such ions was shown to be the sarcoplasmic reticulum, to which they were quickly returned and stored by what became known as a ‘calcium pump’.