Linkages have been suggested between observed interdecadal variability of sea‐ice and salinity in the North Atlantic. A plausible mechanism for generating such variability through the interaction of sea‐ice and the thermohaline circulation (THC) is examined in a zonally‐averaged THC model coupled to a thermodynamic ice model. A self‐sustaining interdecadal oscillation arises through the feedbacks between salinity anomalies induced by the sea‐ice melting‐freezing process and anomalous meridional heat transport associated with the THC. The oscillation time scale is not associated with any oceanic time scales but fundamentally depends on ice‐THC coupling. The period is quite robust to stochastic forcing, although the regularity is strongly affected.