Bernt Karsten Øksendal (born 10 April 1945 in Fredrikstad) is a Norwegian mathematician.
He completed his undergraduate studies at the University of Oslo, working under Otte Hustad.
In 1992, he was appointed as an adjunct professor at the Norwegian School of Economics and Business Administration, Bergen, Norway.
In 1982 he taught a postgraduate course in stochastic calculus at the University of Edinburgh which led to the book Øksendal, Bernt K. (1982).
In 2005, he taught a course in stochastic calculus at the African Institute for Mathematical Sciences in Cape Town.