One hundred and forty-four newly weaned pigs (21 days of age) were used to determine the effect of partially replacing animal protein sources with black solider fly larvae meal (BSFLM) in nursery diets on growth performance, gut morphology, and immune response. After weaning, pigs were placed in 24 pens (6 pigs per pen) and pens were randomly assigned to one of four dietary treatments (study d 0; n = 6), which were fed over 3 phases (phases I, II, and III were fed for 7, 14, and 21 days, respectively). Two nursery diets were formulated with 25% (LowFF) and 50% (HighFF) of the animal protein sources replaced by full fat BSFLM. Conventional nursery diets including animal protein sources without (CON-) and with antibiotics (220 mg Aureomycin per kg of complete feed; CON+) served as controls. On day 8, two pigs per pen were sacrificed to collect organ weights and for intestinal histomorphological measurements. On days 9 and 23, two pigs per pen were vaccinated with the novel antigen ovalbumin (OVA). Blood samples were collected on days 9, 23, and 38 to assess concentrations of plasma haptoglobin and OVA-specific immunoglobulins G (IgG) and IgG1. On day 38, the same two pigs per pen underwent a dermal hypersensitivity test and skin-fold thickness was measured at 0, 6, 24, and 48 h post-intradermal injection with OVA.