Low temperature is among the most frequent stresses met by plants during their lifespan, and a plant's ability to cold-acclimate is a determinant for further growth and development. Although intensive research has provided a good picture of the molecular and metabolic changes triggered by cold, the underlying regulatory mechanisms remain elusive and are thus being actively sought. Recent studies have shed light on the importance of nitric oxide (NO), a ubiquitous signalling molecule in eukaryotes, for plant tolerance to chilling and freezing. Indeed, NO formation following cold exposure has been reported in a range of plant species, and a series of proteins targeted by NO-based post-translational modifications have been identified. Moreover, key cold-regulated genes have been characterized as NO-dependent, suggesting the crucial importance of NO signalling for cold-responsive gene expression. This review provides a picture of our current understanding of the function of NO in the context of plant response to cold. Particular attention is dedicated to the open questions left by the fragmented data currently available concerning NO formation, transduction and biological significance for plant adaptation to low temperature. Although nitric oxide (NO) is now recognized as a versatile actor of stress signalling networks in plants, its involvement in cold stress responses emerged very recently. During the past few years, the identification of proteins and genes targeted by NO signalling, together with the key functions of these targets for cold tolerance, supported the importance of NO for establishing tolerance to low temperature. This review summarizes our current knowledge on this topic by addressing different aspects of NO signalling (generation and removal, impact on protein function and gene expression, overall impact on cold response) and proposing directions for future investigations.