GDF Suez signed an agreement to take on the 9 percent stake in Nabucco West from Austrian energy company OMV Gas and Power.
Nabucco West is designed as an 800-mile natural gas pipeline that will move Azeri natural gas from the Turkish border to European consumers.
"With this commitment to the Nabucco West project, GDF Suez bring its full support to this strategic project and reasserts its position as a key player in European natural gas," Cirelli said in a statement.
The BP-led consortium working offshore Azerbaijan is expected to pick between Nabucco West and the Trans-Adriatic Pipeline next month. GDF Suez said Nabucco West, if selected, would go into service around 2020.
Nabucco Chief Executive Officer Reinhard Mitschek said the entry of GDF Suez reinforces the significant of the pipeline.
"The industry expertise of GDF Suez as the operator of the largest gas transport network in Europe and their status as the second-largest buyer of natural gas in Europe are of immense advantage to the project," he said in a statement.