Microplastics are an emerging pollutant of concern. A large portion of microplastics in the waters arises from washing synthetic textiles in residential and commercial washing machines. Herein we show that it is possible to upcycle this waste to carbon nanomaterials using hydrothermal carbonization. Real microfiber waste was collected using commercially available washer and dryer filters, and then carbonized to yield a few layers graphene or graphite. Via temperature screening analyzing the solid products by SEM, TEM, TGA-DSC, Raman, FT-IR and elemental analysis, two interesting optimum temperatures were detected 250^oC and 300^oC, with a maximum conversion to solid carbon of 25% when the residence time was 4 hours. To this end, raman spectroscopy results indicate the production of carbon nanomaterials. We demonstrate that varying the reaction conditions the carbon production can be tailored towards desired carbon products such as amorphous carbon or graphene/graphite. This is an intriguing method of incorporating textile residue (microfibers) into the circular economy system, and with additional optimization, it will be suitable for industrial scale.