Ilkka Maunu Olavi Niiniluoto (born 12 March 1946) is a Finnish philosopher and mathematician, serving as a professor of philosophy at the University of Helsinki since 1981.

on leave from his position, having been appointed as rector of the University of Helsinki on 1 August 2003, for a five-year period.

On 25 April 2008 he was chosen to succeed Kari Raivio as chancellor of the University of Helsinki, beginning 1 June 2008.

A significant contribution to the philosophy of science, particularly to the topic of verisimilitude or truth approximation, is his Truthlikeness (Synthese Library, Springer, 1987).

Ilkka Niiniluoto is editor-in-chief of Acta Philosophica Fennica, the leading philosophical journal of Finland.