This paper establishes the nature of urban crimes prevalent in Nairobi County, Kenya in the context of Kibera and Karen jurisdictions. The paper adopted a descriptive research design and stratified random sampling technique to enlist respondents into the study. The study sample size comprised of 196 respondents and 10 Key Informants (K-I’s). The main data collection methods were the questionnaire for the main respondents and interviews for K.I’s. Quantitative data was analyzed with the aid of a statistical package for social sciences (SPSS). Frequency distribution tables were used to present data. The findings indicate that; the nature of urban crimes prevalent in Nairobi County in general, specifically in Kibera and Karen jurisdictions were categorized into; violent crimes (44.4%), property crimes (55.4%), and drug-related (10.2%). Violent crimes included; armed robberies, and street robberies. Property crimes included; break-ins, stealing, and muggings. According to 80% of the K.Is, most criminals were mainly unemployed youths, most of them utilizing criminality as a source of livelihood. These youthful criminal gangs waylaid victims going to or from jobs in the evening and early morning to rob or mug them. The study observed that an increase in unemployment led to property crimes, while significant violent crimes were only committed due to the trigger effects of unemployment. This study recommends serious national resource mapping that will factor in industrialization and Job creation for the unemployed. Further, the study recommends Job creation in county governments to discourage rural to urban migrations of job seekers to cities.