Patients with inflammatory bowel disease (IBD) presenting to primary care may experience diagnostic delays. We aimed to evaluate this and assess whether time to diagnosis is associated with clinical outcomes. A retrospective cohort study using English primary care data from January 1, 2010, to December 31, 2019, linked to hospital admission data was undertaken. Patients were followed from the first IBD-related presentation in primary care to IBD diagnosis. Associations of time to diagnosis exceeding a year were assessed using a Robust Poisson regression model. Associations between time to diagnosis and IBD-related emergency hospital admissions and surgery were assessed using Poisson and Cox proportional hazards models, respectively. Of 28 092 IBD patients, 60% had ulcerative colitis (UC) and 40% had Crohn's disease (CD). The median age was 43 (interquartile range, 30-58) years and 51.9% were female. Median time to diagnosis was 15.6 (interquartile range, 4.3-28.1) months. Factors associated with more than a year to diagnosis included female sex (adjusted risk ratio [aRR], 1.23; 95% CI, 1.21-1.26), older age (aRR, 1.05; 95% CI, 1.01-1.10; comparing >70 years of age with 18-30 years of age), obesity (aRR, 1.03; 95% CI, 1.00-1.06), smoking (aRR, 1.05; 95% CI, 1.02-1.08), CD compared with UC (aRR, 1.13; 95% CI, 1.11-1.16), and a fecal calprotectin over 500 μg/g (aRR, 0.89; 95% CI, 0.82-0.95). The highest quartile of time to diagnosis compared with the lowest was associated with IBD-related emergency admissions (incidence rate ratio, 1.06; 95% CI, 1.01-1.11). Longer times to IBD diagnoses were associated with being female, advanced age, obesity, smoking, and Crohn's disease. More IBD-related emergency admissions were observed in patients with a prolonged time to diagnosis.