Problem: Extremely low‐birth‐weight (ELBW) infants require fortification of human milk (HM) to prevent growth failure. Bovine milk–based fortifiers (BOV‐f) may be associated with feeding intolerance and necrotizing enterocolitis. Evidence suggests that an exclusive HM diet (EHMD) using HM‐based fortifier (HM‐f) may improve these outcomes. Intervention: EHMD was introduced as a quality improvement project to improve feeding tolerance in ELBW infants. Method: Implementation included establishing EHMD feeding protocol and growth monitoring. We compared infants receiving HM with BOV‐f (n = 49) with infants receiving an EHMD (n = 15). The primary outcome was a reduction of no oral intake days due to feeding intolerance. Results: The EHMD cohort had a more advanced GA (28 vs 26 weeks; P = .03), more males (66.7% vs 42.9%; P = .02), and higher incidence of SGA (40.0% vs 18.4%; P = .16) compared with the HM‐f group. The EHMD cohort had fewer days with no oral intake (2 vs 5; P < .005), which is insignificant when adjusted for small for gestational age (SGA) (P = .26). The EHMD cohort vs. the HM‐f cohort had a significant decrease in weight and length z‐scores from birth to discharge (−1.09 vs −0.26 [P = .002]; −1.76 vs −0.83 [P = .02]). Inadequate weight gain persisted after adjustment for SGA. Interventions were performed to increase caloric intake and institute milk preparation changes. Conclusion: EHMD improved feeding tolerance in our ELBW infants. Observed growth failure might be skewed by SGA prevalence. We highlight that implementation of EHMD requires close growth assessment, especially for SGA infants.