This study investigated the response of Cabbage (Brassica oleracea L.) varieties to spacing in the Sudan and Northern Guinea savanna zones of Kebbi State, Nigeria, during the 2023/2024 dry season. The experiment was conducted at two locations: Jega, located in the Sudan savanna, and Ribah, situated in the Northern Guinea savanna. Jega is characterized by a semi-arid climate with annual rainfall ranging between 600 and 800 mm, mean temperatures of 28–38 °C during the growing season, and predominantly sandy loam soils of low organic matter content. Ribah, on the other hand, falls within the wetter Guinea savanna zone, with annual rainfall of 900–1,100 mm, moderate temperatures of 25–34 °C, and loamy soils with slightly higher fertility and moisture-retention capacity compared to Jega. These contrasting ecological conditions provided an opportunity to assess variety×spacing responses across different agro-ecological environments. The experiment employed a Randomized Complete Block Design (RCBD) with three replications, involving two cabbage varieties (Grafas and Copenhagen) and six spacing regimes (20 × 20 cm, 20 × 25 cm, 20 × 30 cm, 30 × 30 cm, 30 × 35 cm, and 30 × 40 cm). Growth parameters assessed included plant height, number of leaves, leaf area, leaf area index, days to 50% heading, crop growth rate, and relative growth rate. Yield and yield-related parameters measured were fresh plant weight, head diameter, head weight, number of folded leaves, total yield, and harvest index. The results revealed that variety Grafas consistently outperformed Copenhagen across most growth and yield parameters. Grafas produced taller plants, more leaves, heavier heads, larger head diameters, and higher harvest index, demonstrating superior adaptability to semi-arid conditions. Spacing also exerted a strong influence on performance. Wider spacing (30×40 cm) enhanced plant height, head size, and head compactness due to reduced intra-plant competition for light, nutrients, and water. Conversely, closer spacing (20 × 20 cm) produced higher yields per hectare as a result of high plant population density, although individual heads were smaller and less compact. Correlation analysis showed strong positive relationships between yield and traits such as plant height, number of leaves, fresh plant weight, head diameter, and folded leaves, indicating that these can be used as reliable predictors of cabbage productivity. The study concludes that Grafas is the superior variety for both Sudan and Northern Guinea savanna environments of Kebbi State.