Transfer RNAs (tRNAs) are primarily viewed as static contributors to gene expression. By developing a high-throughput tRNA profiling method, we find that specific tRNAs are upregulated in human breast cancer cells as they gain metastatic activity. Through loss-of-function, gain-of-function, and clinical-association studies, we implicate tRNAGluUUC and tRNAArgCCG as promoters of breast cancer metastasis. Upregulation of these tRNAs enhances stability and ribosome occupancy of transcripts enriched for their cognate codons. Specifically, tRNAGluUUC promotes metastatic progression by directly enhancing EXOSC2 expression and enhancing GRIPAP1—constituting an “inducible” pathway driven by a tRNA. The cellular proteomic shift toward a pro-metastatic state mirrors global tRNA shifts, allowing for cell-state and cell-type transgene expression optimization through codon content quantification. TRNA modulation represents a mechanism by which cells achieve altered expression of specific transcripts and proteins. TRNAs are thus dynamic regulators of gene expression and the tRNA codon landscape can causally and specifically impact disease progression. Display omitted •Specific tRNAs are upregulated in highly metastatic breast cancer cells•TRNAs promote stability and translation of transcripts enriched for their codons•TRNAGluUUC drives metastasis by directly upregulating EXOSC2 and enhancing GRIPAP1 A new tRNA profiling method reveals that specific tRNAs are upregulated in metastatic breast cancer cells and drive metastasis by enhancing stability and translation of transcripts enriched for their cognate codons.