For understanding the place of income in smartphone diffusion, this paper aims to find out the dependence of smartphone market indicators on income level worldwide and in the developing economies. The strength of the relationship between above mentioned variables identifies the speed of smartphone diffusion influenced by income. For current purposes, secondary data from 189 countries were analyzed by using Hierarchical Cluster Analysis and Chi-square analysis. The results confirmed that income level influences smartphone purchase and diffusion. However, the strength of the relationship between income and smartphone market indicators is diverse globally and in developing countries. In developing countries, the strength of the relationship is smaller in comparison with the overall results. It means that income level has weak moderating effect in smartphone diffusion, and it cannot be considered as a key indicator of smartphone diffusion in developing countries according to results of the analysis in 2016 and the arithmetic mean of 2013-2017 years.