Collagen is the main component that makes up the internal structure of animals and is extensively used in several industrial fields including food, materials, chemicals, and pharmaceuticals. Despite the variety of preparation methods available, there is significant potential for enhancing the yield of recombinant collagen produced through engineered Pichia pastoris (P. pastoris). Increasing the copy number of the recombinant type III human collagen α1 (hlCOLIII) gene to improve the level of expression of the recombinant protein and co-expression of molecular chaperones to alleviate the resulting endoplasmic reticulum stress further promotes hlCOLIII secretion. By optimizing transcription driven by the AOX1 promoter and improving translation efficiency, a strain of P. pastoris expressing hlCOLIII efficiently was constructed, achieving a yield of 10.3 g/L in a 5 L fermenter. Further, hlCOLIII demonstrated notable antioxidant capacity and performed well in bioactivity analyses, including cell proliferation, migration, and adhesion. This study lays a solid foundation for the scalable industrial production of recombinant collagen and opens new avenues for its exploration in advanced biomedical materials.