We investigate fabrication of functional conductive carbon paste onto a plastic substrate using a laser. The method allows simultaneous sintering, patterning, and functionalization of the carbon paste. Experiments are carried out to optimize the laser-processing parameters. It is shown that sheet resistance values obtained by laser sintering are close to the one specified by the manufacturer using the conventional sintering method. Additionally, a heat transfer analysis using numerical methods is conducted to understand the relationship between the temperature during sintering and the sheet resistance values of sintered carbon wires. The process developed has the potential of producing carbon-based electronic components on low-cost plastic substrates.