Kaisa Sofia Matomäki (born April 30, 1985) is a Finnish mathematician specializing in number theory.
Since September 2015, she has been working as an Academic Research Fellow in the Department of Mathematics and Statistics, University of Turku, Turku, Finland.
Her research includes results on the distribution of multiplicative functions over short intervals of numbers; for instance, she showed that the values of the Möbius function are evenly divided between +1 and -1 over short intervals.
These results, in turn, were among the tools used by Terence Tao to prove the Erdos discrepancy problem.