The use of a hardwood lignosulfonate (HLS) precursor along with electrospinning technology was studied to produce HLS-based carbon fibers. The production of the fibers helped to determine the appropriate processing parameters in the HLS carbon fiber production process. The processing parameters examined were the heating rate (POR) and the treatment temperature (POT) in the preoxidation process; the heating rate (C1R) and the treatment temperature (C1T) were in the low-temperature carbonization phase; and the carbonization temperature (C2T) and temperature holding period (C2t) were in the high-temperature carbonization phase. The results revealed that preoxidation with a POR of 1 °C/min and a POT of 250 °C generated favorable properties, particularly enhancing the fiber mat integrity and the fiber carbon content. The designed two-phase carbonization process was found to be satisfactory in increasing carbon fiber yields and enhancing fiber mat integrity. A C1R value of 1 °C/min and C1T of 400 °C facilitated favorable properties in the produced carbon fibers. Furthermore, a prolonged C2t increased the fiber carbon content but reduced the carbon fiber yield. The highest fiber carbon content occurred with a C2t of 3 h and a C2T of 1200 °C.