Critical slope stability analysis has proven to be a reliable technique which could be used in gully erosion risk assessments. The integration of experimental and stability modelling has assisted extensively in the analysis of natural slopes. In the current paper, several geotechnical properties and slope parameters were studied in an attempt to characterize gullying processes and risk in southern Anambra State, Nigeria. Field mapping, geotechnical analyses, geostatistical analyses, and limit equilibrium simulations were integrated to achieve the research objectives. The field measurements showed that most of the gullies are characterized by high slope angles ranging between 18° and 85°. Based on the geotechnical analysis, the soil slopes were observed to be highly vulnerable to landsliding. Principal component and regression analyses efficiently captured the interrelationships between the analyzed erosion gully parameters. Several slope stability models were used to estimate the factor of safety (FS) of the slope materials. It was revealed that most of the slopes are unstable and vulnerable whereas others are critically to moderately stable. Furthermore, while the slopes recorded FS in the range of 0.82–1.72 in unsaturated condition, FS of 0.70–1.33 was observed for saturated condition. This result indicated that the gully slopes are more vulnerable to failure by erosive forces in wet season, due to rainwater infiltration and pore-water pressure buildup. Gully slopes within the Nanka Formation showed higher failure vulnerability than those in Ogwashi and Benin formations. The details of this study would be helpful towards the mitigation of landslide hazards in the study area.