Population mobility, particularly among street vendors, is experienced in all urban centres world over. Some of the movements include those from city centres outwards to the periurban and the adjacent rural areas. The reverse human movements are sometimes also vastly experienced but they are not a focus of this paper. In the quest for knowledge about population migration and population mobility of street vendors from other regions of Tanzania to Dar es Salaam and Coast regions necessitated for an analysis to be done on the sources of migrations, i.e. regions from which they originated, through which they settled for the first time, call it transitional regions; to the permanent settlement areas, i.e. destination. The analysis was done by levels of education and types of business they engaged in. A survey was conducted in Dar es Salaam and the Coast regions among 100 street vendors in 10 centres located along the Morogoro road; whereby 10 respondents were interviewed at each centre. Data were processed using the Statistical Package for Social Scientists (SPSS) deploying descriptive statistics. The paper, therefore, seeks to identify the existing patterns of population mobility; and based on the characteristics of the migrants, who are street vendors, uncover the existing relationship between human population mobility and the pace of urbanization. The main findings of the study indicated that mobility of street vendors was highly influenced by presence of business opportunities which enhanced urban growth denoted by emergence of urbanism. The mobility demonstrated a three stage process, i.e. moving away from the source, living in transitional centre (regional town) prior to moving to Dar es Salaam and Coast Region, i.e. destination. Dar es Salaam had the highest levels of street vendors’ internal mobility with dominance of intraurbanmobility. Men and women aged 30 years and above constituted the majority of the street vendors migrants in Tanzania.