Nanocellulose, a sub-micron cellulose powder, was investigated as a potential filler excipient to enhance the tabletability of acetaminophen (APAP). Due to its high specific surface area, nanocellulose was expected to outperform the tabletability enhancement provided by microcrystalline cellulose (MCC), a common tablet filler used in pharmaceutical tablets. Results showed that nanocellulose is inferior to MCC when used as a conventional filler. This is due to the difficulty in deaggregating and dispersing aggregates of nanocellulose using a typical dry blending process. To improve its effectiveness, nanocellulose prepared as a suspension was blended or "co-processed" with APAP using a twin-screw process. Microscopy images show that the twin-screw process coats the APAP with nanocellulose. The tabletability of APAP was significantly improved by low concentrations of nanocellulose up to 1.10% w/w. Such remarkable improvement allowed acetaminophen to be processed into tablets without any additional excipients. This study shows that nanocellulose can be used as a highly functional additive to enhance tabletability at low concentrations.