Tenderness is the most important organoleptic characteristic of meat, and various methods have been developed to improve it. The purpose of this experiment was to evaluate the effect of different conditioning treatments of broiler carcasses on pH, cooking losses, shear values, R-values, and sensory tenderness of breast meat. All measurements were collected for breast muscle as follows: after 24 h of carcass aging (T1); after 24 h of carcass aging with muscle tensioning (T2); after 24 h of carcass aging with muscle tensioning, followed by muscle collection and marination in CaCl2 (T3); after hot-boning 15 min following slaughter (T4); after hot-boning 15 min following slaughter and marination in CaCl2 (T5). pH values in meat treated with CaCl2 were significantly lower than those in untreated meat from the aged carcass group (T3) or the hot-boning group (T5). Breasts from carcasses aged for 24 h (T1, T2, and T3) showed lower cooking loss than breasts harvested immediately after slaughter (T4 and T5). CaCl2 marination produced meats with cooking losses significantly higher than those observed for untreated meats. Regardless of muscle tensioning or marination treatments, aging of the carcass for 24 h (T1, T2, and T3) produced meats with lower shear values than those from hot-boned carcasses (T4 and T5). Hot-boned breasts treated with CaCl2 (T5) were judged less tender by panelists than breasts aged under muscle tensioning (T2 and T3).