In this study, a simple method was developed to incorporate commercially available magnetic AlNiCo powders into nanocellulose composite solids and aerogels. Fine magnetic powders can be homogeneously integrated using only ultrasonic agitation. Simply grinding standard industrial powders within a mortar and pestle was sufficient to create a fine enough starting material, although care must be taken not to magnetize the powder to prevent agglomeration. The resulting suspension could be freeze dried to form ultralight ferromagnetic aerogels or dried to form hard magnetic solids or films. Homogeneous nanocellulose composites with mass ratios of up to 50% AlNiCo were readily achieved. The resulting materials showed magnetic behavior as expected for a standard AlNiCo composite, with a homogeneous and submicron magnetic particle distribution. The resultant properties compared favorably to processes using preformed magnetic nanoparticles as a starting material. The simplicity of the technique, which uses standard industrial reagents, could be useful in developing sustainable and economically feasible methods for creating nanocellulose composite materials.