Synthetic biology offers boundless possibilities and revolutionary changes to material fields. One remarkable outcome of interdisciplinary integration of synthetic biology and material science is the development of environmentally friendly polyhydroxyalkanoates (PHAs), which serve as ideal alternatives to petroleum-based plastics. PHAs are a family of linear biopolyesters synthesized by various microorganisms as their intracellular storage materials for energy and carbon sources. With at least 150 various monomers, PHAs exhibit diverse structures, material properties, and applications, collectively known as “PHAomics”. When reprograming microbial genomes via synthetic biology and metabolic engineering, in combination with the feeding of special precursors, tailor-made PHAs with defined structures and varied properties can be synthesized. PHAs has been extensively studied in both academia and industry in the last few decades, leading to the commercialization of some PHAs. Next generation industrial biotechnology (NGIB) based on halophilic Halomonas spp. as chassis has been developed to overcome the limitations of current industrial biotechnology. NGIB offers a long lasting, open and continuous, energy and freshwater-saving bioprocess using low-cost mixed substrates and allows morphology engineering for simplified downstream processing. NGIB facilitates low-cost production of various PHAs in large scale. This review introduces PHAomics and summarizes the diverse properties of PHAs produced via NGIB. It primarily focuses on the composition, structure, and material properties of PHAs, as well as their extensive applications in biodegradable plastics, medical implants, medicine, drug delivery carriers, energy sources, and potential smart materials. Additionally, it covers the strategies and tools for strain engineering and their achievements in the tailor-made biosynthesis of PHA using reprogrammed Pseudomonas spp. and Halomonas spp. Finally, this review discusses strategies on how to further reduce the production cost and improve material properties of PHAs. This review summarizes the progresses on the low-cost customized synthesis of PHA biomaterials by synthetic biology, demonstrating the integration of biology and chemistry.