This study was conducted to develop a scale that can measure the relationship between the Halo effect and the evaluations made by referees about athletes' performances, who should make subjective evaluations in sport competitions. The population of the study consisted of 247 referees who were on duty in various sports and in different classifications and who were registered for the year 2023. The items of the scale were produced by the researcher with the support of the literature and it was determined that the items provided content validity (CVI=0.925). After the pilot study, reliability analysis was performed and Alpha=0.970 was found. Exploratory factor analysis was applied to reveal the construct validity of the scale and Alpha=0.972 was found. The fit statistics calculated by confirmatory factor analysis were found to be compatible with the previously determined factor structure of the scale at an acceptable level. In the results of the analyses, it was determined that factor loadings were high, standard error values were low, t values were significant and the construct validity of the predetermined factor structure was confirmed. In addition, as a result of the item discrimination test, it was determined that the scale was able to make a sensitive discriminative measurement (p<0.05). It was found that the scale provided convergent and divergent validity (CR>AVE>0.5), ICC values related to the agreement between test-retest measurements were high, there was no difference between test-retest correlation values, and the scale made reliable measurements based on short time (p<0.05). As a result, it was concluded that the "Perceived Halo Effect Scale in Referee Evaluations in Sport" is a valid and reliable scale.