N6-Methyladenosine (m6A) is the most common RNA modification in eukaryotic mRNAs and growing evidence suggests the crucial roles of m6A and its regulators in human tumorigenesis. Recent studies have shown that the m6A regulators promote tumorigenesis of various types of cancer. However, the underlying molecular mechanisms of m6A regulators in breast cancer remain largely unknown. We therefore assessed the genetic alterations, expression and prognostic role of m6A regulators in breast cancer using openly available data from The Cancer Genome Atlas (TCGA). Analysis of TCGA data revealed that m6A regulators including , , and were upregulated in breast cancer tissues, and the expression level significantly correlated with intrinsic subclasses and nodal metastasis. Importantly, we found for the first time that and were frequently amplified which contribute to the overexpression of and transcripts, thereby promoting breast cancer progression. Moreover, overexpression of and were associated with poor prognosis of breast cancer patients. Therefore, YTHDF1 and YTHDF3 serve a crucial role in the pathogenesis of breast cancer, which are potentially useful for prognosis stratification and therapeutic target for breast cancer.