Thorne was born in Logan, Utah on June 1, 1940. His father was a Chemist, his mother Alison (née Comish) Thorne, was an Economist and the first woman to receive a Ph.D. in the discipline from Iowa State College. Raised in an academic environment, two of his four siblings also became professors. Thorne's parents were members of The Church of Jesus Christ of Latter-day Saints (Mormons) and raised Thorne in the LDS faith, though he now describes himself as atheist. Regarding his views on science and religion, Thorne has stated: "There are large numbers of my finest colleagues who are quite devout and believe in God [...] There is no fundamental incompatibility between science and religion. I happen to not believe in God."

Thorne and Linda Jean Peterson married in 1960. Their children are Kares Anne and Bret Carter, an Architect. Thorne and Peterson divorced in 1977. Thorne and his second wife, Carolee Joyce Winstein, a professor of biokinesiology and physical therapy at USC, married in 1984.

Thorne rapidly excelled at academics early in life, winning recognition in the Westinghouse Science Talent Search as a senior at Logan High School and becoming one of the youngest full professors in the history of the California Institute of Technology at age 30. He received his B.S. degree from Caltech in 1962, and Ph.D. degree from Princeton University in 1965. He wrote his doctoral thesis, Geometrodynamics of Cylindrical Systems, under the supervision of relativist John Wheeler. Thorne returned to Caltech as an associate professor in 1967 and became a professor of theoretical physics in 1970, the william R. Kenan, Jr. Professor in 1981, and the Feynman Professor of Theoretical Physics in 1991. He was an adjunct professor at the University of Utah from 1971 to 1998 and Andrew D. White Professor at Large at Cornell University from 1986 to 1992. In June 2009 he resigned his Feynman Professorship (he is now the Feynman Professor of Theoretical Physics, Emeritus) to pursue a career of writing and movie making. His first film project was Interstellar, on which he worked with Christopher Nolan and Jonathan Nolan.

Thorne has written and edited books on topics in gravitational theory and high-energy astrophysics. In 1973, he co-authored the textbook Gravitation with Charles Misner and John Wheeler; that according to John C. Baez and Chris Hillman, is one of the great scientific books of all time and has inspired two generations of students. In 1994, he published Black Holes and Time Warps: Einstein's Outrageous Legacy, a book for non-scientists for which he received numerous awards. This book has been published in six languages, and editions in Chinese, Italian, Czech, and Polish are in press. In 2014, Thorne published The Science of Interstellar in which he explains the science behind Christopher Nolan's film Interstellar; Nolan wrote the foreword to the book. In September, 2017, Thorne and Roger D. Blandford published Modern Classical Physics: Optics, Fluids, Plasmas, Elasticity, Relativity, and Statistical Physics, a graduate-level textbook covering the six major areas of physics listed in the title.

Why is it that a cylindrical bundle of magnetic field lines will not implode, while spherical stars will implode under their own gravitational force? Thorne tried to explore the theoretical ridge between the two phenomena. He found out eventually that the gravitational force can overcome all interior pressure only when an object has been compressed in all directions. To express this realization, Thorne proposed his hoop conjecture, which describes an imploding star turning into a black hole when the critical circumference of the designed hoop can be placed around it and set into rotation. That is, any object of mass M around which a hoop of circumference ${\displaystyle {\begin{matrix}{\frac {4\pi GM}{c^{2}}}\end{matrix}}}$ can be spun must be a black hole.

Thorne is known for his ability to convey the excitement and significance of discoveries in gravitation and astrophysics to both professional and lay audiences. In 1999, Thorne made some speculations on what the 21st century will find as the answers to the following questions:

He was elected to hold Lorentz chair for the year 2009 Leiden University, the Netherlands.

With Anna Żytkow, Thorne predicted the existence of red supergiant stars with neutron-star cores (Thorne–Żytkow objects). He laid the foundations for the theory of pulsations of relativistic stars and the gravitational radiation they emit. With James Hartle, Thorne derived from general relativity the laws of motion and precession of black holes and other relativistic bodies, including the influence of the coupling of their multipole moments to the spacetime curvature of nearby objects. Thorne has also theoretically predicted the existence of universally antigravitating "exotic matter" – the element needed to accelerate the expansion rate of the universe, keep traversable wormhole "Star Gates" open and keep timelike geodesic free float "warp drives" working. With Clifford Will and others of his students, he laid the foundations for the theoretical interpretation of experimental tests of relativistic theories of gravity – foundations on which Will and others then built. As of 2005, Thorne was interested in the origin of classical space and time from the quantum foam of quantum gravity theory.

Kip Thorne was selected by Time magazine in an annual list of the 100 most influential people in the American world in 2016.

In 2017, Thorne was awarded the Nobel Prize in Physics along with Rainer Weiss and Barry C. Barish "for decisive contributions to the LIGO detector and the observation of gravitational waves".