This study examined the effects of photoperiod, light intensity, and their interaction on blood acid‐base balance, metabolites, and electrolytes in broilers under environmentally controlled rooms in 2 trials. The study consisted of a factorial arranged in a randomized complete block design with 9 treatments that consisted of 3 photoperiod (continuous [23L:1D] from d 8 ‐ d 56; intermittent [2L:2D], and short [8L:16D] from d 8 ‐ d 48 and 23L:1D from d 49 ‐ d 56, respectively) and exposure to 3 light intensities (10, 5.0 and 0.5 lx) from day 8 through d 56 at 50% RH. A total of 540 1‐d‐old (30 male/30 female) chicks were randomly distributed into 9 chambers. Feed and water were provided ad libitum. Venous blood samples were collected on d 14, 28, 42, and 56. Short photoperiod significantly (P ≤ 0.05) reduced BW, pH level, pO2, sO2, and Ca2+, while significantly (P ≤ 0.05) elevated pCO2, Hct, Hb, and McHc concentrations. There was only an effect of light intensity on K+. Acid‐base regulation during short photoperiod and light intensity exposure had not deteriorated despite higher pCO2 that consequently decreased blood pH, due to a respiratory acidosis. Plasma corticosterone was not affected by photoperiod, light intensity or their interaction, indicating that exposure of broiler chickens to short photoperiod markedly affects some physiological blood variables without inducing stress in modern broilers grown to heavy weights.