Our findings establish that FMT induces remission in refractory IBD via ecosystem network rewiring, and that IFX-FMT exhibits additive effects, supporting further trials of microbiome-directed adjunctive strategies.<h4>Importance</h4>This study provides mechanistic and clinical insights into the therapeutic effects of fecal microbiota transplantation (FMT) in inflammatory bowel disease (IBD), particularly when combined with the anti-tumor necrosis factor (anti-TNF) biologic infliximab (IFX). Here, TNF is linked to inflammatory bowel disease.