The nature of digital hydraulic systems may cause severe pressure pulsation problems. For example, switched inertance hydraulic systems can be used to adjust or control flow and pressure by a means that does not rely on dissipation of power, but they have noise problems because of the pulsed nature of the flow. An effective method to reduce the noise is needed that does not impair the system performance and efficiency. This article reports on an initial investigation of an active attenuator for pressure pulsation cancellation in a switched inertance hydraulic system. Using the designed noise attenuator, the pressure pulsation can be decreased effectively by superimposing an anti-phase control signal. A high-performance piezoelectric valve was selected and used as the secondary path actuator in terms of its fast response and wide bandwidth. Adaptive notch filters with the filtered-X least mean square algorithm were applied for pressure pulsation attenuation, while a frequency-domain least mean square filter was used for secondary path identification. A ‘switched inertance hydraulic system’ in a flow booster configuration was used as the test rig. Experimental results show that excellent cancellation was achieved using the proposed method, which has several advantages over passive noise control systems, being effective for a wide range of frequencies without impairing the system’s dynamic response. The method is a very promising solution for pressure pulsation cancellation in hydraulic systems with severe noise or vibration problems.