NiMn-based Heusler-type multiferroic alloys have attracted intensive attention due to their fascinating multifunctional properties such as magnetic shape memory, magnetocaloric effect, and magnetoresistance. The recently elucidated superparamagnetism and superspin glass behaviors in these alloys could greatly impact their multifunctional properties. This article provides an overview on the recent research progress on superparamagnetism and superspin glass behaviors in NiMn-based multifunctional alloys. The corroboration of these magnetic behaviors in the low-temperature phase is demonstrated and the possible origin of the magnetic clusters responsible for these magnetic behaviors is discussed. The open scientific issues in this research area are highlighted.