The purpose of this article is to study the influence of internal governance mechanisms on the diversification and growth strategy of Saudi firms in the non-oil sector. Considering a sample of 70 Saudi companies observed over the period 2006-2014 and using the Linear Regression method, correlated panels, corrected standard errors (PCSEs). Our empirical results show the structure of the board of directors that motivates Saudi firms to run less risk and diversify all activities rather than refocus the group's activity. We have shown that the presence of the largest shareholder has a positive effect on the diversification strategy. These results support our basic assumptions that firms with a high concentration of capital favor diversification rather than the risk that accompanies the growth of the firm's overall activities. In line with our reasoning and consistent with previous research, our main contribution is that the control mechanisms are not neutral with regard to the diversification strategy. The verification of these assumptions in the Saudi context makes it possible to enrich the verification of the positive relationship between governance and the diversification of firms.