Combustion processes have been an important factor in human progress. However, the exhaust gases can contain high-risk species, either by its toxicity to living beings or for contributing to environmental degradation. Among different techniques used for combustion pollutant control, it can be highlighted the use of non-equilibrium plasmas. This kind of plasma is a source of chemically active species such as radicals, ionized and metastable species, and also free electrons which promote the ionization and dissociation of the background gas molecules. In this study, a gliding arc discharge generated in a fuel-rich premixed mixture was applied to a swirl global fuel-lean flame, both of them generated in a mixture of air and natural gas. The discharge electrical diagnostic was performed to verify the influence of the gas flow rate and the mixture composition on the discharge repetition frequency. Both the increase of the total gas mass flow rate and of the fuel amount in the mixture increase the discharge repetition frequency. The chemical analysis of the plasma-assisted combustion exhaust gas showed that the discharge acts as a source of oxygen and hydrogen species (O, H, H2, OH). It accelerates the hydrocarbon oxidation and lowers the levels of carbon monoxide, improving the combustion process.