We examine the time- and frequency-dependent co-movements between stock and government bond yield returns for four major markets in sub-Saharan Africa. We employ the bi-, partial, and multiple wavelets techniques to evaluate the influence of COVID-19 cases on the fundamental relationship between bond and stock market returns. We further assess the lead-lag connectedness between these asset classes to ascertain their potency to offer diversification advantages in the COVID-19 pandemic era. From the bi-wavelet analysis, we find that the stock-bond dynamics in SSA markets mimic a non-homogeneous pattern that is attributable to interdependence. Our findings divulge that marginal COVID-19 cases do not drive the co-movement between stock and bond yield returns at all time scales. With no contagious spillovers found, the multiple wavelet correlations explicate that the interrelations between the two asset classes are attributed to their interdependence in the long term. We find safe-haven benefits for short- and medium-term investors during the COVID-19 pandemic. In the long term, for all market conditions, the extent of connectedness between stocks and bonds lessens any diversification prospects. We underscore the potency of South African bond and stock returns to lead and/or lag all other markets across investment horizons, both in normal and stressed trading periods. Devising measures that strengthen the markets for bonds to create consistent diversification opportunities for investors is essential to attracting international capital flows. We discuss the implications of our findings.