In this thesis, I will examine how activist athletes, particularly Naomi Osaka, construct their self-identity within social media. In Osaka's case, I will explore how Naomi Osaka's identities as black and a woman interact with her activism and politics through social media, and if Osaka's activist messaging is responded to by producers and consumers of social media. Do they respond to Osaka's activism, and what dominant structures are produced, reproduced, and perpetuated by this phenomenon? The main interpretive framework that I employ is Black Feminist theory, and specifically toward examining how black women have historically been erased in the discourse surrounding social justice issues. In other words, Western patriarchal society has not allowed black women to tell their own stories, nor adequately represent themselves in the social justice discourse. In this thesis, I examine Osaka's construction of her identity and activist ideals through her Twitter posts. These posts run parallel to social justice movements (i.e., Black Lives Matter), and sport events that Osaka participates in (i.e., U.S. Open and Cincinnati Masters). To carry out this project, I use Critical Discourse Analysis (CDA) to examine the social, cultural, and political implications regarding the language (and thus sentiments) of media and fans that respond to Osaka's activism vis-à-vis tweets that she produces. I explain how and where Osaka's activism (i.e., what she chooses to speak out about within the societal order) originates, if producers and consumers of social media respond to it, and what that tells us of where we are as a culture in the United States today. The results indicate that sentiments from repliers to Osaka's activism were highly contested; some repliers agreed with Osaka's expressed concern for marginalized groups, while others found it inappropriate for an athlete to speak on socio-political issues. Studying Naomi Osaka's construction of her activism and politics, moreover the responses to it, will aid in understanding how mediated identities are formed in contested ways – and whereby black women continue to find new ways towards liberation from systems that seek to erase them.