A mixer assembly unit, especially for an exhaust system of an internal combustion engine of a vehicle, includes a mixer body (48) with an incoming flow side (58) and with an outgoing flow side (60); and a carrier element (24) with a carrier element body (44) enclosing the mixer body (48) radially on an outside in relation to a mixer longitudinal axis. The mixer body (48) includes a plurality of flow deflection elements (62) and at least one holding area (70). The carrier element (24) includes a counter holding area (46) in association with a holding area (70). The counter holding area (46) is connected in substance to the holding area (70). The counter holding area (46) overlaps the holding area (70) at least partly radially on a side oriented in a direction of the outgoing flow side (60) of the mixer body (48).