This paper examined the effect of ICT adoption on Nigerian and Johannesburg Stock Exchange markets – the leading exchanges in Africa. Analysis was anchored on panel data metrics of ICT adoption, control and transaction capacities measures of the exchanges. Findings: ICT adoption had heterogeneous effects during the study periods. Use of the Internet had negative effect on the market indices, except capitalisation. Some of the regressors had no significant effects on individual merits, but aggregate effects were significant. The regressors well-explained total variation in the stock market measures. Consequently, this paper considered ICT adoption to be sine quo non to the growth and development of Africa’s stock exchange and financial markets; and recommended more investment in ICT innovations and adoptions for greater regional and continental co-operation and possible integration into global settings.