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We present the results from a multiyear radio campaign of the superluminous supernova (SLSN) SN 2017ens, which yielded the earliest radio detection of an SLSN to date at the age of ∼3.3 yr after explosion. SN 2017ens was not detected at radio frequencies in the first ∼300 days but reachedL_ν≈ 10²⁸erg s⁻¹cm⁻²Hz⁻¹atν∼ 6 GHz, ∼1250 days post explosion. Interpreting the radio observations in the context of synchrotron radiation from the supernova shock interaction with the circumstellar medium (CSM), we infer an effective mass-loss rate$\dot{M}\approx {10}^{-4}{M}_{☉}{\mathrm{yr}}^{-1}$atr∼ 10¹⁷cm from the explosion’s site, for a wind speed ofv_w= 50–60 km s⁻¹as measured from optical spectra. These findings are consistent with the spectroscopic metamorphosis of SN 2017ens from hydrogen poor to hydrogen rich ∼190 days after explosion reported by Chen et al. SN 2017ens is thus an addition to the sample of hydrogen-poor massive progenitors that explode shortly after having lost their hydrogen envelope. The inferred circumstellar densities, implying a CSM mass up to ∼0.5M_☉, and low velocity of the ejection suggest that binary interactions (in the form of common-envelope evolution and subsequent envelope ejection) play a role in shaping the evolution of the stellar progenitors of SLSNe in the ≲500 yr preceding core collapse.