The study aimed to assess the influence of social media's ethnic-based negative narration on the unity of law enforcement personnel. The involved Ethiopian Federal police commission at Addis Ababa branches. The study also attempts to find out how and why federal police personnel use social media? Especially after the political reform takes place in April 2018. The researcher employed a mixed-method approach. The quantitative data gathered through survey questionnaires and qualitative data also gathered through face-to-face and phone interview methods. The number of respondents in survey questionnaires was 97 and interview participants were 10. All participants are purposively selected from Ethiopian Federal police commission. Quantitative data is analyzed and interpreted by SPSS version 23 software. The study finding showed that most of the Federal police personnel are highly influenced by the negative broadcasting of social media ethnic-based content, Furthermore, all informants from survey questionnaires and interview participants confirm that social media negative narration against ethnicity severely damage the unity of law enforcement personnel and law enforcement service. According to the collected data Facebook identified as the main source of ethnic-based negative social media posts, YouTube was the second-largest social media platform in disseminating racial slur, identity critics and other identity based disgraceful narrations. Among the participants, 93.8 percent of survey questionnaire respondents confirm social media has imposed negative repercussions on law enforcement services. Again 89.7 percent of survey questionnaire respondents agreed on the pervasive effect of social media negative narration against the ethnicities. The researcher recommends that the Federal government in general; the Federal police commission, in particular, must give attention to the effect of social media's negative repercussions against the unity of the law enforcement personnel and the law enforcement service. Moreover, training and media literacy courses have to be delivered on regular basis. Furthermore, effective law must be implemented.