For two years, the tomatoes (cv. ‘Belle’ and ‘Clarabella’), ungrafted, self-grafted and grafted onto the ‘He-man’ rootstock, were grown under two irrigation regimes, i.e., partial-root zone drying (PRD) and fully irrigated (FI), to investigate whether grafting can alleviate drought stress and promote water-use efficiency (WUE). The grafted plants under the FI regime had the highest vegetative growth, which was the result of more leaves and greater leaf area and were only significantly different from the PRD grown ungrafted plants. The grafted plants had the highest yield as a result of the greater number of larger fruits and the yield did not differ between the irrigation treatments. No differences were found in the leaf NPK concentrations, while the Ca and Mg were higher under the PRD regime. The ungrafted plants under the PRD regime had the highest total soluble solids and acidity in the fruit juice. The grafted plants had a significantly higher WUE, more pronounced in the PRD regime. The different types of irrigation did not influence the vegetative growth and the yield in the greenhouse grown grafted tomato. The PRD and rootstock effects should be additionally investigated with deficit irrigation.