A rotary vane magnetorheological energy absorber, which enables a longer stroke capability in a more compact configuration than conventional magnetorheological devices, is disclosed. This novel device design is attractive for applications where long stroking capability, high force dynamic range, device size, and device weight are important. The improved magnetorheological energy absorber comprises an internal or external flow valve and a hollow body enclosing fixed and rotary vanes as well as magnetorheological fluid. Fluid flow in the valve is restricted as a solenoid is activated, thus adjusting the capability of the device to react torque. Various flow valve configurations are disclosed, as well as various motion translation mechanisms for translating linear motion to rotary motion for use of the rotary vane magnetorheological energy absorber. The improved design minimizes the amount of magnetorheological fluid required as compared to conventional linear stroke energy absorbers, thus minimizing device weight.