The political context of the 1990s generated significant changes in the territorial structure and migratory behaviour of Romanian regions, as well as a severe economic decline and an increase in development disparities between the East and West. The main objective of this research is to analyse the empirical relationship between economic growth and the internal migration of the workforce, on both a national and regional level, by applying the standard production function and using panel data based on the annual series of eight regions for 19 years (2000–2018). To outline the effects on the structures of the economy, an empirical analysis of the relationship between economic growth and the structural development of the economy, considering the migration of the workforce among the five main sectors of the economy, was carried out. On a regional level, in the North West, North East and Bucharest Ilfov regions, internal migration positively influences economic growth, with migration in rural regions having a high impact. However, for the Central, South East, South West Oltenia, and West regions, migration has a negative influence on economic growth. The results regarding the effects of these structures on the economy indicate a high, but negative, influence on regional economic growth due to the active agricultural sectors in all eight regions of Romania. On the other hand, the construction sector determines positive effects in all regions of Romania.