This study examined political parties� representation in parliament influencing public policy formulation (at agenda setting) in Uganda�s nascent hydrocarbon industry. The study followed both a research objective and hypothesis. The researcher applied a descriptive cross-sectional survey research design to guide the study. The research adopted both quantitative and qualitative approaches and data was collected from 218 respondents selected out of 490 Members of Parliament. The researcher collected both quantitative and qualitative data which was analyzed using descriptive and inferential statistics and thematic content analysis respectively. The findings revealed that political parties� representation is a significant determinant of public policy formulation in Uganda�s nascent hydrocarbon industry. It was concluded that there is a strong positive relationship between political parties� representation and public policy formulation in Uganda�s nascent hydrocarbon industry. It is recommended that political parties should emphasize party discipline and numbers in order to increase seats in parliament. Political parties should emphasize discipline among their members such that they toy the party line and vote according to the caucus decision; political parties should always endeavor to increase their numbers in parliament in order to influence public policy formulation.