Self-sufficiency (autonomy) in growth signaling, the earliest recognized hallmark of cancer, is fuelled by the tumor cell’s ability to ‘secrete-and-sense’ growth factors; this translates into cell survival and proliferation that is self-sustained by auto-/paracrine secretion. Using breast cancer cells that are either endowed or inept in growth signaling autonomy, here we reveal how tumor cell autonomy impacts cancer progression. Autonomy is associated with enhanced molecular programs for stemness, immune evasiveness, and epithelial-mesenchymal plasticity (EMP) across the entire mesenchymal spectrum. Autonomy is both necessary and sufficient for anchorage-independent growth factor-restricted growth, resistance to anti-cancer drugs and metastatic progression. Transcriptomic and proteomic studies show that autonomy is associated with self-sustained EGFR/ERBB signaling, a required signal for re-epithelialization. A gene expression signature was derived (a.k.a., autonomy signature) which revealed that autonomy is induced in circulating tumor cells (CTCs), the precursor tumor cells that re-epithelialize to initiate metastases. Autonomy in CTCs tracks therapeutic response and prognosticates outcome. Autonomy is present during reversible (but not stable) EMT and requires EGFR/ERBB signaling. These data support a role for growth signaling autonomy in the blood-borne dissemination of human breast cancer.