v3.26.1
Investments - Net carrying amount (Details) - EUR (€)
€ in Millions
12 Months Ended
Dec. 31, 2025
Dec. 31, 2024
Dec. 31, 2023
Investments      
Book value € 13,155 € 14,150 € 12,630
Associates      
Investments      
Book value 4,047 4,619  
Associates | LabAnalysis Environmental Scienze Srl      
Investments      
Book value € 26    
% of the investment in associate 30.00%    
Associates | Abu Dhabi Oil Refining Company (TAKREER)      
Investments      
Book value € 1,980 € 2,275  
% of the investment in associate 20.00% 20.00%  
Associates | QatarEnergy LNG NFE (5)      
Investments      
Book value € 661 € 633  
% of the investment in associate 25.00% 25.00%  
Associates | Ithaca Energy Plc      
Investments      
Book value € 486 € 725  
% of the investment in associate 35.92% 37.17%  
Associates | ADNOC Global Trading Ltd      
Investments      
Book value € 192 € 165  
% of the investment in associate 20.00% 20.00%  
Associates | Coral FLNG SA      
Investments      
Book value € 184 € 231  
% of the investment in associate 25.00% 25.00%  
Associates | LG-Eni BioRefining Co Ltd [Member]      
Investments      
Book value € 93 € 56  
% of the investment in associate 49.00% 49.00%  
Associates | United Gas Derivatives Co      
Investments      
Book value € 71 € 79  
% of the investment in associate 33.33% 33.33%  
Associates | Novis Renewables Holdings Llc      
Investments      
Book value € 66 € 74  
% of the investment in associate 49.00% 49.00%  
Associates | Bluebell Solar Class A Holdings II LlC      
Investments      
Book value € 62 € 72  
% of the investment in associate 99.00% 99.00%  
Associates | Var Energi ASA      
Investments      
% of the investment in associate 63.04% 63.04%  
Associates | Other      
Investments      
Book value € 226 € 309  
Joint ventures      
Investments      
Book value 9,016 9,449  
Joint ventures | Azule Energy Holdings Ltd      
Investments      
Book value € 4,634 € 5,211  
% of the investment in joint venture 50.00% 50.00%  
Joint ventures | E&E Algeria Touat BV      
Investments      
Book value € 671 € 646  
% of the investment in joint venture 66.00% 54.00%  
Joint ventures | St. Bernard Renewables Llc      
Investments      
Book value € 657 € 806  
% of the investment in joint venture 50.00% 50.00%  
Joint ventures | Saipem SpA      
Investments      
Book value € 581 € 528  
% of the investment in joint venture 21.80% 21.61%  
Joint ventures | SeaCorridor Srl      
Investments      
Book value € 411 € 485  
% of the investment in joint venture 50.10% 50.10%  
Joint ventures | Vårgrønn AS      
Investments      
Book value € 374 € 406  
% of the investment in joint venture 65.00% 65.00%  
Joint ventures | Cardon IV SA      
Investments      
Book value € 370 € 351  
% of the investment in joint venture 50.00% 50.00%  
Joint ventures | Mozambique Rovuma Venture SpA      
Investments      
Book value € 366 € 382  
% of the investment in joint venture 35.71% 35.71%  
Joint ventures | GreenIT SpA [member]      
Investments      
Book value € 140 € 111  
% of the investment in joint venture 51.00% 51.00%  
Joint ventures | Eni CCUS Holding      
Investments      
Book value € 136    
% of the investment in joint venture 50.01%    
Joint ventures | 2023 Sol IX Llc      
Investments      
Book value € 131 € 149  
% of the investment in joint venture 73.62% 73.59%  
Joint ventures | Lotte Versalis Elastomers Co Ltd      
Investments      
Book value € 81 € 61  
% of the investment in joint venture 50.00% 50.00%  
Joint ventures | Mangistau Power B.V      
Investments      
Book value € 75 € 51  
% of the investment in joint venture 51.00% 51.00%  
Joint ventures | 2024 Sol XV Llc      
Investments      
Book value € 67    
% of the investment in joint venture 47.47%    
Joint ventures | 2022 Sol VII Llc      
Investments      
Book value € 53 € 61  
% of the investment in joint venture 75.24% 75.26%  
Joint ventures | 2025 Bateria II Llc      
Investments      
Book value € 53    
% of the investment in joint venture 33.92%    
Joint ventures | Hergo Renewables SpA [member]      
Investments      
Book value € 35 € 33  
% of the investment in joint venture 65.00% 65.00%  
Joint ventures | Mangistau Renewables B.V.      
Investments      
Book value € 35 € 21  
% of the investment in joint venture 51.00% 51.00%  
Joint ventures | 2024 Sol XVI Llc      
Investments      
Book value € 31    
% of the investment in joint venture 40.58%    
Joint ventures | Societa Oleodotti Meridionali - SOM SpA      
Investments      
Book value € 13 € 18  
% of the investment in joint venture 70.00% 70.00%  
Joint ventures | LabAnalysis Environmental Scienze Srl      
Investments      
Book value   € 26  
% of the investment in joint venture   30.00%  
Joint ventures | Other      
Investments      
Book value € 102 € 103  
Investments in unconsolidated entities controlled by Eni      
Investments      
Book value 92 82  
Investments in unconsolidated entities controlled by Eni | Other      
Investments      
Book value € 92 € 82