Nylons are widely used polyamides produced in large amounts from petrochemical-derived monomers. The production of fully biobased nylons using fermentatively produced diacids and diamines has been of great interest but not yet realized. Here, we report synthesis and characterization of bionylon-4,4 and -5,4, two rarely studied nylons, using succinic acid, 1,4-diaminobutane, and 1,5-diaminopentane produced by fermentation of metabolically engineered bacteria. The synthesized bionylons exhibit excellent thermotolerance and water absorptivity. To illustrate applicability, bionylons are also successfully used as a matting agent to reduce surface gloss of poly(acrylonitrile-co-styrene-co-acrylic) rubber. Furthermore, bionylon4,4 and -5,4 are found to be biodegradable, providing further environmental benefit upon disposal. The strategy for the synthesis of fully biobased nylons comprising fermentative monomer precursor production and purification, polymerization, characterization, and application development reported here can serve as a guideline for synthesizing other fully biobased polymers from renewable resources.