The authors examine how the Mandarin-Cantonese relationship has been ideologically and discursively perceived and constructed in China's language policy and planning, and Chinese people's reaction over the years by drawing on theories in critical discourse analysis, systemic functional linguistics, and language ideology. Data collection includes language policies, government officials' dissemination, and Chinese citizens' online comments, which are analyzed at ideological, discursive, and linguistic levels. The findings suggest that both the language policies and the officials were driven more by an ideology of uniformity that elevates Mandarin as opposed to other local dialects such as Cantonese. The authors also identify three main categories of competing ideologies underpinning Chinese netizens' reactions. Reactions aligned with the centripetal ideology favor sustaining the unity of China against a sense of superiority of Cantonese speaking people. Neutral reactions emphasize the ease of communication and language identities without being inclined to the extreme of aggressive Mandarin popularization. Positions aligned with centrifugal ideology uphold Cantonese as a unique language and maintaining Cantonese as a right and duty. The authors conclude with a discussion of whether promoting diversity and linguistic rights can achieve uniformity in a dialogic way.