The study aimed to define the role of the knowledge economy in promoting the economic growth of 136 countries, using the cross-section approach method. Knowledge Economy is measured by the KEI (Knowledge Index), which is defined by the World Bank. Economic growth is measured by GDP per capita in constant prices of US dollars for the year 2010. According to this value, the countries are divided into four groups in step with the World Bank classification. The study found that there is a positive effect of the knowledge economy index on the economic growth at the level of significance of 1%, this effect increases as the income level increases.