Improving broiler performance during heat stress has been the aim of many researches, and one of most common approach is to increase dietary metabolizable energy (ME), which may increase nutrients availability and improve energy efficiency by both reducing heat increment (HI) and increasing ME conversion into net energy (k). This study aimed to evaluate the effects of increasing ME levels on performance, nutrient digestibility and energy balance of 19 to 41 d old broilers kept under cyclic heat stress (16 h of 23 ± 2°C and 8 h of 32 ± 2°C; 60 ± 2% RH). A total of 336 male broilers were used, distributed in a completely randomized design with 4 treatments and 6 replicates of 14 birds each. Treatments consisted of 4 diets containing 19% CP and 4 ME levels (2,980, 3,080, 3,180 and 3,280 kcal/kg), which were obtained by the addition of soybean oil. Data were submitted to ANOVA and the means were compared by Tukey and SNK test for performance and energetic metabolism, respectively (α = 0.05). Weight gain, feed intake, viability and productive efficiency ratio were not influenced by ME levels (P > 0.05). However, broilers presented a better feed conversion ratio when fed with 3,280 kcal/kg, followed by 3,180 kcal/kg (P = 0.003). Moreover, the lowest feed cost per kg of live weight was observed with 2,980 kcal/kg, followed by broilers that consumed 3,080 kcal/kg of feed (P = 0.028). The digestibility of CP and EE increased linearly with ME increase in diet (P < 0.001). The consumption of ME adjusted to zero nitrogen balance was not affected by diet treatment (P > 0.05), but a higher heat production was observed in broilers that received diets with the lowest ME level (P = 0.012). HI was higher in broilers fed with 2,980 kcal/kg diet (93.9 kcal/kg^0.75/day) (P = 0.016). The dietary ME levels had a linear effect over net energy (P < 0.021), but k remained constant between diets (P > 0.05). We conclude that ME level influences on performance and energetic metabolism.