Abstract Aims Liver fibrosis and cirrhosis are a consequence of a Fontan physiology, and determine prognosis. It is unclear whether non-invasive assessment of liver pathology is helpful to provide clinically relevant information. The aims of this study were to assess the spectrum of Fontan-associated liver disease (FALD) and usefulness of non-invasive methods to assess biopsy confirmed liver fibrosis. Methods and results Hepatic screening of consecutive patients consisted of a blood panel, ultrasonography, elastography, contrast-enhanced magnetic resonance imaging (MRI)/computed tomography (CT) scan, and liver biopsy (scored with Fontan specific fibrosis scores and collagen proportionate area; CPA). Fibrosis parameters, varices, ascites, and splenomegaly were measured on imaging. Thirty-eight of 49 referred patients (27 ± 6.6 years, 73.7% male) underwent the complete screening protocol. Liver fibrosis on biopsy was present in all patients, and classified as severe (Stages 3–4) in 68%. Median CPA was 22.5% (16.9–29.5) and correlated with individual fibrosis scores. ELF® and liver stiffness were elevated, but MELD-XI scores were low in all patients. Fibrosis severity neither correlated to ELF® and liver stiffness, nor to (semi-) quantitative fibrosis parameters on MRI/CT. Varices were present in 50% and hyperenhancing nodules in 25% of patients, both independent of fibrosis stage, but varices were associated with higher CPA values. Conclusion The FALD spectrum includes both hepatic congestion and severe fibrosis, with signs of portal hypertension and hyperenhancing nodules as significant manifestations. Routine imaging, transient elastography, and serum biomarkers are unable to accurately assess severity of liver fibrosis in this cohort. Future research should focus on validating new diagnostic tools with biopsy as the reference standard.