Early data suggest fecal microbiota transplant (FMT) may treat hepatic encephalopathy (HE). Optimal FMT donor and recipient characteristics are unknown. We assessed the safety and efficacy of FMT in patients with prior overt HE, comparing five FMT donors. We performed an open‐label study of FMT capsules, administered 5 times over 3 weeks. Primary outcomes were change in psychometric HE score (PHES) and serious adverse events (SAEs). Serial stool samples underwent shallow shotgun metagenomic sequencing. Ten patients completed FMT administration and 6‐month follow‐up. Model for End‐Stage Liver Disease (MELD) score did not change after FMT (14 versus 14, p = 0.51). Thirteen minor adverse events and three serious adverse events (two unrelated to FMT) were reported. One SAE was extended‐spectrum beta‐lactamase Escherichia coli bacteremia. The PHES improved after three doses of FMT (+2.1, p < 0.05), after five doses of FMT (+2.9, p = 0.007), and 4 weeks after the fifth dose of FMT (+3.1, p = 0.02). Mean change in the PHES ranged from −1 to +6 by donor. Two taxa were identified by random forest analysis and confirmed by linear regression to predict the PHES— Bifidobacterium adolescentis (adjusted R² = 0.27) and B. angulatum (adjusted R² = 0.25)—both short‐chain fatty acid (SCFA) producers. Patients who responded to FMT had higher levels of Bifidobacterium as well as other known beneficial taxa at baseline and throughout the study. The FMT donor with poorest cognitive outcomes in recipients had the lowest fecal SCFA levels. Conclusion: FMT capsules improved cognition in HE, with an effect varying by donor and recipient factors (NCT03420482).