Using annual data from 1980-2014, this paper employs a random effect model to estimate the effect of regional integration on private investment in East African Community (EAC). Levin-Lin-Chu Test (LLC) and Pedroni Cointegration Test were used to investigate the properties of data with respect to unit root and cointegration respectively while the Hausman Test was used to select the random model. The error correction model was used to capture the short-run dynamics in the model. The findings suggest that regional integration (proxied by intra-EAC openness), has a positive significant effect on private investment in the EAC. Hence the respective EAC governments should sustain policies that promote free trade so as to boost private investment in the region through the removal of tariffs which leads to efficiency in production and hence economies of scale.