Marina Ratner grew up in a household with parents who were both scientists. She excelled in mathematics as a high school student, encouraged by one of her teachers. In 1956 she applied to enter Moscow State University, which had just recently opened its doors to Jewish students. She studied mostly mathematics with a bit of physics and the required Marxism and Communist Party history courses. She received her M.A. degree in 1961. She then went to work for Professor A. N. Kolmogorov in his applied statistics group and taught in his school for gifted high school students. During this time she also gave birth to her daughter.
In 1965 Ratner returned to Moscow State University, earning her Ph.D. in 1969 under the supervision of Yakov G. Sinai. Her thesis was on "Geodesic Flows on Unit Tangent Bundles of Compact Surfaces of Negative Curvature." For the next year she was an assistant at the High Technical Engineering School in Moscow, but was fired when she applied for a visa to emigrate to Israel. Ratner lived In Israel from 1971 to 1975, teaching as a lecturer at the Hebrew University of Jerusalem and the Pre-academic School of that university. In 1975 she was hired by the University of California at Berkeley as an acting assistant professor. She has been at Berkeley ever since, rising to her present rank of professor in 1982.
Ratner's main work has been in the area of ergodic theory, an area of mathematics related to probability theory and statistics that originated in the study of thermodynamics. In 1992 she was elected to the American Academy of Arts and Sciences, and the following year was elected to the National Academy of Sciences (NAS). In 1994 the NAS awarded her the John. J. Carty Award for the Advancement of Science for her noteworthy and distinguished accomplishments in mathematics, in particular, her "striking proof of the Raghunathan conjectures" that has provided number-theoretic information about quadratic forms. Ratner also received the 1993 Ostrowski Prize in recognition of this work. This prize is awarded biennially "to one or more mathematicians who during the preceding five years have accomplished the highest scientific achievement in pure mathematics or in the theoretical foundations of numerical analysis." The description of the 2005 book Ratner's Theorems on Unipotent Flows by Dave Witte Morris says that "The theorems of Berkeley mathematician Marina Ratner have guided key advances in the understanding of dynamical systems."