Bio-based resins for UV-assisted photopolymerization vat 3D printing have received immense research interest. 3D printing has initiated the 4.0 industrial revolution and is expected to squeeze in more production industries, including making materials for outdoor applications. Weathering investigations have been devoted mainly to fossil acrylic polymers. This research aims to close the gap in understanding bio-based acrylic 3D-printed polymer weathering performance. QUV accelerated weathering was used on vegetable oil-based 3D-printed compositions with nanofibrillated cellulose (NFC) as reinforcing filler. Discoloration, cracking, FTIR measurements of surface chemical degradation, and bulk properties evaluated by changes in mechanical performance were used to characterize materials performance during weathering. NFC reinforcement delays the yellowing and cracking during 1000 h of weathering. After weathering, increased flexural stress and strain were achieved with 0.5 wt% NFC loading. Chemical analysis reveals simultaneous photocleavage and additional crosslinking of the macromolecular chains. The glass transition temperature increased by up to 20 °C. NFC introduction in bio-based polymers increased of weathering endurance and mechanical performance. The NFC is compatible with and a perspective filler in bio-based acrylic resins for 3D printing applications.