Systemic lupus erythematosus (SLE) and inflammatory bowel disease (IBD) are chronic systemic autoimmune conditions marked by aberrant immune activation. The pathogenesis of both diseases is multifactorial, involving a complex interplay between genetic susceptibility and environmental influences. Although the simultaneous presence of SLE and IBD is uncommon in clinical practice, this report describes a pediatric female patient who presented with abdominal pain as the primary manifestation and was ultimately diagnosed with both SLE and ulcerative colitis. Treatment with infliximab (IFX), a tumor necrosis factor-α inhibitor, in combination with immunosuppressive therapy led to significant alleviation of her autoimmune and gastrointestinal symptoms. This case highlights the importance of maintaining a high index of suspicion for underlying IBD when evaluating SLE patients with unexplained gastrointestinal complaints—particularly abdominal pain or diarrhea—that do not correlate with typical disease flares.