This study assessed the effect of Spirulina ( Arthrospira platensis ), individually and in combination with exogenous enzymes, on growth performance, carcass traits, and meat quality of broiler chickens. One hundred and twenty Ross 308 male chickens were allocated into 40 battery brooders, with 3 birds per cage, and fed ad libitum a corn-based diet during the first 21 D of the trial. The experimental period lasted from day 21 to 35, during which birds were fed 4 different diets: a corn-soybean basal diet, taken as the control group, a basal diet containing 15% Spirulina ( MA ), a basal diet containing 15% Spirulina plus 0.005% Rovabio Excel AP ( MAR ), and a basal diet containing 15% Spirulina plus 0.01% lysozyme ( MAL ). Body weight gain ( P < 0.001) and feed conversion rate ( P < 0.001) were improved in control chickens, when compared with those fed with Spirulina. In addition, Spirulina increased the length of duodenum plus jejunum in relation to the other treatment ( P < 0.01). Chickens on the MAL diet showed a considerable increase in digesta viscosity ( P < 0.05) compared with the control group. Breast and thigh meats from chickens fed with Spirulina, with or without the addition of exogenous enzymes, had higher values of yellowness (b*) ( P < 0.001), total carotenoids ( P < 0.001), and saturated fatty acids ( P < 0.001), whereas n-3 polyunsaturated fatty acid ( P < 0.01) and α-tocopherol ( P < 0.001) decreased, when compared with the control. In conclusion, the incorporation of 15% Spirulina in broiler diets, individually or combined with exogenous enzymes, reduced birds' performance through a higher digesta viscosity, which is likely associated with the gelation of microalga indigestible proteins. In addition, cell wall of Spirulina was successfully broken by the addition of lysozyme, but not by Rovabio Excel AP. Therefore, we anticipate that the combination of lysozyme with an exogenous specific peptidase could improve the digestibility of proteins from this microalga and avoid their detrimental gelation.