This study evaluated the effects of three quince rootstocks (Quince-A, Quince-C, and BA-29) on the flowering, fruit set, yield, fruit quality, and vegetative growth of the ‘Hafif Çukurgöbek’ loquat (Eriobotrya japonica Lindl.) cultivar under Mediterranean climatic conditions. The experiment was conducted in Hatay, Türkiye, between 2018 and 2020 using a factorial arrangement based on a randomized complete block design (RCBD). Each rootstock treatment consisted of 30 trees with six trees per replicate and five replications. Significant effects of the Year, Rootstock, and their interaction were detected for most parameters measured. Frost (–2.5 °C) during flowering and heat stress (42 °C) before harvest in 2020 significantly reduced fruit set and yield. Quince-C and BA-29 rootstocks consistently induced higher flowering and fruit set rates, larger fruit size, and greater fruit yield than Quince-A. Trees grafted on Quince-A induced smaller but sweeter fruits with higher total soluble solids (TSS) and pH. Vegetative growth, including shoot length, trunk diameter, and canopy size, was the most vigorous in trees on Quince-C, followed by those on BA-29, whereas Quince-A reduced tree vigor. These preliminary results suggest that dwarfing quince rootstocks, particularly BA-29 and Quince-C, are suitable for high-density loquat orchards.