Knowledge of financial distress is important to conserve firms’ financial health, ultimately contributing to a country’s economy. This is essential within the African context, where economic conditions are strained. The financial sustainability of firms is under pressure, evident from the number of firms that ceased to exist. Theoretically, capital structure decisions remain a conundrum for firms. Research has been dedicated to refining the understanding of how capital structure relates to corporate finance decisions, amongst others, for the long-term survival of firms. Data of listed industrial firms for two large African economies has been used, South Africa and Nigeria, from 2014 to 2022. This study utilised the Altman Z-score (Z-score) as a financial sustainability measure to determine its relationship with the financing decision, proxied by the debt-equity ratio. The panel regression technique was utilised as analysis, with firm size and the lag of the Z-score as control variables. An insignificant relationship between capital structure and financial sustainability was found for both South African and Nigerian datasets. The original contribution includes a comparative view of South Africa and Nigeria, providing an African perspective on capital structure and financial sustainability within the industrial industry. The capital structure decision does not threaten the financial sustainability of the firms. This is noteworthy, especially since the capital structure, on average, showed that Nigerian firms were relying more on debt than South African firms. This result expands the theoretical knowledge of capital structure. Practically, decision-makers have more freedom in making financing decisions without threatening financial sustainability.