The sulfur compounds existing in commercial fuels, such as thiols, benzothiophenes, and sulfides, are harmful to the human health and contribute to the air pollution. Among the different methods proposed for the lowering of sulfur content of commercial fuels to less than 10 ppm is the adsorptive desulfurization. Furthermore, escalating environmental concerns are intensifying the need to utilize renewable and waste resources for the manufacture of high-value engineered materials. Lignin is an abundant natural polymer, while poly(ethylene terephthalate) is a major compound of municipal waste. Here, we have combined these two polymers for the manufacture of activated carbon nanofibers, and we have tested them for the adsorption of sulfur compounds from model fuels. Initially, electrospun nanofibers of varying average diameters were prepared (80 - 800 nm) using different mass ratios between lignin and recycled-PET (50/50 - 90/10). After carbonizing them, the carbon nanofibers which exhibited the highest BET surface area were found to be the ones prepared from a lignin/r-PET mass ratio of 50/50 and of 395 nm average fiber diameter. These carbon nanofibers were then chemically activated with KOH and the resulting activated carbon nanofibers were used for the adsorption of 4,6-dimethylbenzothiophene from a model diesel fuel. The adsorption results showed that these activated carbon nanofibers have a very high adsorption capacity for 4,6-dimethyldibenzothiophene, reaching the value of 123.4 mg/g.