Prior to his appointment as President at Pomona College in 2003, he was the dean of the physical sciences division at the University of Chicago.

In December 2018, the American Academy of Arts and Sciences announced that Oxtoby would serve as its 47th president, succeeding Jonathan Fanton.

As a research chemist, Oxtoby is author or co-author of more than 158 scientific articles[3] on subjects such as light scattering, chemical reaction dynamics and phase transitions.

He has received fellowships from the Guggenheim, Alexander von Humboldt, Camille and Henry Dreyfus, Alfred P. Sloan, Danforth and National Science foundations.

Theoretical chemist David Tannor, who is the Hermann Mayer Professorial Chair in the department of chemical physics at the Weizmann Institute of Science in Israel, did his post-doc work with Stuart Rice and David Oxtoby at the University of Chicago.