Miljenko Mumlek (born 21 November 1972 in Varaždin) is a Croatian former footballer who played as a midfielder until being sentenced to prison for match fixing.

Born in Varaždin, Mumlek started his professional career in his hometown with NK Varteks in early 1992 and went on to establish himself as one of the club's key players during the 1990s.

In the summer of 1999, Mumlek left Varteks for Dinamo Zagreb (then known as Croatia Zagreb) and went on to make four appearances for the club in the UEFA Champions League group stage, appearing in both home and away fixtures against Manchester United and Olympique de Marseille before Dinamo were knocked out of the competition after finishing 4th out of 4 teams in their group, one point behind the 3rd-place Sturm Graz.

He made his full international debut on 20 April 1994 in a 4–1 defeat for Croatia against Slovakia in Bratislava, coming on as a half-time substitute for Dean Računica.

Following the Kirin Cup tournament, he remained uncapped for over four years, apart from appearing for Croatia B in a friendly match against France on 19 January 1999.