The objective of this study is to investigate the interactions during co-pyrolysis of kraft lignin/lignite and subsequent gasification of co-pyrolysis-formed char. The co-pyrolysis behavior of kraft lignin and lignite was conducted in analytical pyrolysis-gas chromatography/mass spectrometry (Py-GC/MS) and thermogravimetric analysis (TGA). Then, the CO2 gasification reactivity of pyrolysis-formed char was also examined in TGA. The experimental results showed that synergy was observed during co-pyrolysis of kraft lignin and lignite, resulting in promoting the formation of several lignin-derived compounds, such as 2,6-dimethylphenol, trans-isoeugenol, anisole, vanillin, and guaiacylacetone. The CO2 gasification reactivity of lignite-derived chars was also obviously promoted as a result of the addition of lignin. The optimal proportion of kraft lignin in the blend may be 30% according to the experimental results from both pyrolysis and gasification. The synergy during co-conversion of kraft lignin and lignite is mainly attributed to the mutual catalytic effects of inherent alkali and alkaline earth metals in kraft lignin and lignite. The study may provide useful data for optimizing the co-conversion process of kraft lignin and lignite.