The company will use the funds for the construction or upgrade of 460km high-voltage and 3,800km medium-voltage and low-voltage lines and cables.
As part of the project, which is planned to be implemented over the period 2015 to 2017, around 3,300 transformers will also be installed or upgraded.
The program will help to connect around 45,000 new system users while enhancing reliability of the electricity supply and reduce losses.
EIB Poland vice-president responsible for lending László Baranyay said: "We therefore particularly welcome this agreement with ENEA, as the project will ensure a secure supply to new customers through the expansion of the company’s electricity network."
Enea management board president Krzysztof Zamasz said: "We have ambitious investment plans and implement them consistently according to our strategy."
EIB has provided about €3bn to support the energy projects since it started operations in 1990 in Poland.
