The son of John Jay Gergen, the Chair of the Mathematics Department at Duke University, and Aubigne Munger (née Lermond), Gergen grew up in Durham, North Carolina. He had three brothers, one of whom is David Gergen, the prominent political analyst. After completing public schooling, he attended Yale University. Graduating in 1957, he subsequently became an officer in the U.S. Navy. He then returned to graduate school at Duke University, where he received his PhD in psychology in 1963. His dissertation advisor was Edward E. Jones. Gergen went on to become an Assistant Professor in the Department of Social Relations at Harvard University, where he also became the Chairman of the Board of Tutors and Advisors for the department and representative to the university's Council on Educational Policy.
In 1967, Gergen took a position as Chair of the Department of Psychology at Swarthmore College, a position he held for ten years. At various intervals, he served as visiting professor at the University of Heidelberg, the University of Marburg, the Sorbonne, the University of Rome, Kyoto University, and Adolfo Ibanez University. At Swarthmore, he spearheaded the development of the academic concentration in interpretation theory. In an attempt to link his academic work to societal practices, he collaborated with colleagues to create the Taos Institute in 1996. He is currently Gil and Frank Mustin Professor Emeritus of Psychology and Senior Research Professor at Swarthmore, the Chairman of the Board of the Taos Institute, and an adjunct professor at Tilburg University.
Gergen is married to Mary M. Gergen, Professor Emeritus at Penn State University, and a major contributor to feminist psychology and performance inquiry. She is the author of over 50 articles and is the co-author (with Ken Gergen) of "Social Construction". They publish the Positive Aging Newsletter with a readership of around 20,000
Gergen's earliest studies challenged the presumption of a unified or coherent self. He then raised questions about the value of altruism, by exploring the ways in which helping others leads to the recipient's resentment and alienation.
A major point in Gergen's career was his 1973 article "Social Psychology as History". In the article, he argues that the laws and principles of social interaction are variable over time, and that the scientific knowledge generated by social psychologists actually influences the phenomena it is meant to passively describe. For example, studying obedience to authority may reduce the likelihood of obedience. He argued therefore that social psychology was not fundamentally a cumulative science, but was effectively engaged in the recording and transformation of cultural life. The article proved contentious, receiving criticism, such as from Barry R. Schlenker. The developing dispute became known as the "Gergen-Schlenker debate" and touched topics around the metatheory of social psychology. Karl E. Weick later took Warren Thorngate's contribution to that dispute to formulate Thorngate's postulate of commensurate complexity, a theorem revolving around research methodology in social sciences.