The European Union’s main strategy for promoting economic convergence is cohesion policy. All EU funds are based on the authority’s selection of regions and program developments, with amounts and targeted projects chosen and distributed in each area of the selected EU country. Ever since the cohesion policy has been implemented, it has been used to boost economic growth, overcome regional disparities, allocate jobs, provide a sustainable economic environment, and increase regional convergence. But this is not true for every region as many parts of the EU cohesion policy might still be ineffective or bring just marginal changes. The main aim of the thesis was to check the cohesion policy’s effectiveness, involving different writers’ ideas with their detailed research to conclude whether the cohesion policy since being introduced has brought any changes in the EU regions. But on the other hand, billions of euros may be spent by the EU to improve regional growth and eliminate regional disparities, but this is not always sufficient. Based on the results of analyses we have studied in this thesis; cohesion policy effectiveness is only possible when internal economic growth is stabilized. If a country is corrupt, regions will find it challenging to develop. Many areas in Central, Southern, and Eastern Europe struggle to overcome regional inequalities brought on by failed policies, economic crises, and unstable economies even when given adequate funds by the EU.