Around the world, the tomato is considered the most important vegetable because of the extent of the cultivated area. In addition, it requires vast amounts of irrigation but little is known about the management of deficit irrigation. This study aims to evaluate the effect of regulated deficit irrigation (RDI) on development of crop and fruit quality for cherry tomatoes (ʽLazarinoʼ and ʽSummerbrixʼ). Two different cherry cultivars were used during two crop cycles (autumn and spring). RDI was scheduled with an initial period of no water stress and with a period of deficit from the beginning of the flowering, with a threshold of midday leaf water potential of around −1 MPa. It was found that the response to the irrigation treatment was affected by the season and even by the cluster considered. During the autumn cycle, there were no clear differences in yield despite water stress being mild but still significant. In the spring cycle, yield reduction peaked with different responses between cultivars. Water stress reduced fruit weight and fruit number per cluster in cv Summerbrix, producing a continuous decrease throughout the harvest period. In cv Lazarino, a yield reduction was detected only at the end of the harvest period and was related to the decrease in fruit weight and the number of inflorescence. The application of RDI reduced water by 85% and increased the content of soluble sugar, carotenoids and total phenols in both cultivars and cycles.