Poultry ectoparasites are the basic cause of retarded growth, low liveliness and poor condition of birds directly by inducing irritation, discomfort, tissue damage, blood loss, toxicosis, allergies and dermatitis which in turn reduce the quality and quantities of meat and egg production and indirectly by being mechanical or biological vectors of pathogens. A cross-sectional study was conducted from November 2020 to April 2021 to identify and estimate the prevalence of ectoparasites of chicken managed under a backyard system in the selected area of Boloso Sore district of Wolaita zone, southern Ethiopia. A total of 322 chickens of different age groups, breeds and both sexes were selected by simple random technique and examined for ectoparasite. From the total, 56.52%(182/322) of chickens were infested with one or more species of ectoparasites that mainly grouped into fleas 30.34%(98/322), lice 21.7%(70/322) and fowl tick 4.34%(14/322), there by six species of ectoparasites were identified. Among them, Echidnophaga gallinacean (stick tight flea) 30.34%(98/322) was the most prevalent ectoparasite species followed by lice species (Menopon gallinae 11.80% (38/322), Menacanthus stramineous 6.21%(20/322), Goniocotes gigas 2.48% (8/70) and Goniocotes gallinae 1.24%(4/322) while the least identified was fowl tick (Argas persicus) 4.34%(14/322). Age of the chicken was shown statistically significant (p<0.05) association with the infestation of ectoparasites in which young chicken was found more (72.5%) infested than adults (27.5%). Also, there was a statistically significant (P<0.05) difference in the prevalence rate of ectoparasites between both sexes of the chicken, in which females (71.4%) was higher than that of male chicken (28.6%). The local breed was found more highly infested (57.1%) than exotic breeds (42.9%) but the difference was not statistically significant (P>0.05). There was statistically nonsignificant (P>0.05) flea infestation in adults 34.14% (43/126) than in young 28.06% (55/196), females 31.34% (63/201) than males 20.66% (25/121), and local breed 31.76% (54/170) than exotic breed 28.95% (44/152). Lice prevalence was statistically nonsignificant (p-value >0.05) higher in adults 38.89% (49/126) than young 10.71% (21/196), female 25.87% (52/201) than males 14.88% (18/121) and local breed 24.12% (41/170) than exotic breed 19.08% (29/152). Generally, the study indicated that the external parasites were highly prevalent in backyard chickens in the study area, which was associated with a lack of attention to the hygienic management system, treatment and control practices which necessitate the application of integrated prevention and control measures like awareness creation to the community on the overall effect of ectoparasites on the productivity of poultry and prevention methods.