The aim of this study was to determine the effect of stevia and ginger extracts (SGE) on growth performance, serum biochemical parameters, organ weights and antioxidant activity in quails under heat stress (HS). A total of 180, 6-week-old male quails were divided into four groups, five quails each, with six replicates. The added extract doses were: 0 (control), 0.5 and 1.0% of the diet for treatments 1–6, respectively. The thermoneutral group (TN) was kept at a temperature of 21 ± 2 °C for 28 days, and the heat stress group (HS) was exposed to 21 ± 2 °C for 18 h and 33 ± 2 °C (10.00–16.00) for 6 h. HS exposure adversely affected performance parameters compared to quails kept at TN, as reflected by lower final body weight (FBW), body weight gain (BWG), cumulative feed intake (CFI) and cold carcass weight (CCW), as well as increased feed conversion ratio (FCR) (P < 0.001 and P < 0.0001, respectively). Raising dietary SGE level linearly increased FBW (P < 0.011), BWG (P < 0.025) and CCW (P < 0.001), while it decreased FCR (P < 0.026). Quails exposed to HS conditions had higher serum malondialdehyde (MDA) (P < 0.0001), creatine kinase (CK) (P < 0.0001), aspartate aminotransferase (AST) (P < 0.006) and triiodothyronine (T3) (P < 0.0001) levels than those reared under TN conditions. SGE supplementation decreased serum MDA (P < 0.003), glucose (P < 0.0001), CK (P < 0.0001), AST (P < 0.0001), T3 (P < 0.001) and thyroxine (T4) (P < 0.024) levels compared to the control groups. While heart and liver weights decreased (P < 0.0001; P < 0.001), an increase in testicular weight was recorded (P < 0.0001). The addition of SGE to the diet during periods of elevated environmental temperature can play an important role in reducing the negative effects of heat stress.