Michael Hartley Freedman (born 21 April 1951 in Los Angeles, California, USA) is a mathematician at Microsoft Research. In 1986, he was awarded a Fields Medal for his work on the Poincaré conjecture, one of the most famous problems of the 20th century.

The Poincaré conjecture asserts that a simply connected closed 3-dimensional manifold is a 3-dimensional sphere. The higher dimensional Poincaré conjecture claims that any closed n-manifold which is homotopy equivalent to the n-sphere must be the n-sphere. When n = 3 this is equivalent to the Poincaré conjecture. Smale proved the higher dimensional Poincaré conjecture in 1961 for n at least 5. Freedman proved the conjecture for n = 4 in 1982 but the original conjecture remains open.

He was awarded a doctorate by Princeton in 1973 for his doctoral dissertation entitled Codimension-Two Surgery. After graduating Freedman was appointed a lecturer in the Department of Mathematics at the University of California at Berkeley. He held this post from 1973 until 1975 when he became a member of the Institute for Advanced Study at Princeton. In 1976 he was appointed as assistant professor in the Department of Mathematics at the University of California at San Diego (UCSD). He spent the year 1980/81 at the Institute for Advanced Study at Princeton returning to UCSD where he was promoted to professor on 1982. He was appointed the Charles Lee Powell chair of mathematics at UCSD in 1985.

He has received numerous other awards and honors including Sloan and Guggenheim Fellowships, a MacArthur Fellowship and the National Medal of Science. He is an elected member of the National Academy of Sciences, the American Academy of Arts and Sciences, and the New York Academy of Sciences.