This study explores polylactic acid (PLA)-based composites reinforced with lignocellulosic nanofibrils (LCNF) processed by spray drying (SD), freeze drying (FD), solvent exchange (SE), and solution transfer (ST) via polyethylene glycol (PEG). The LCNF ranged from near-spherical in the SD LCNF to fibrillar in SE LCNF. SE and FD LCNF agglomerated significantly which inhibits their ability to improve crystallization kinetics and tensile properties. SD LCNF, by its dispersed nature, facilitates high nucleation density, leading to crystallization-induced tensile enhancement. ST LCNF self-assembled into core-shell structures with PEG localizing at the LCNF/PLA interface, reducing agglomeration, yielding significant rheological modification, and greatly enhancing toughness. LCNFs processed by these methods impart differing morphologies that give rise to varying degrees of dispersion and agglomeration, which impacts downstream structures that form after processing and give rise to observed properties. Such material-process-structure-property relationships are foundational in the intelligent design of novel bio-based and biodegradable packaging materials.