Grafting is one of the main techniques used in intensive tomato cultivation to address abnormal weather, diseases, insect pests, and continuous cropping problems. In recent years, due to agricultural labor constraints, the industry has needed to make use of more machinery. In this study, a clamping and cutting arrangement device for Solanaceae scion and stock seedlings was developed; it included a UR5 robotic arm to realize the automatic clamping and cutting of multiple seedlings, to facilitate the mechanized grafting of seedlings. The clamping success rate of eggplant and tomato seedlings using this device was 99%. When working with four seedlings in a single operation, the oblique-cutting success rates for eggplant and tomato seedlings were 97.76% and 94.55%, respectively. Moreover, 404 eggplant seedlings and 384 tomato seedlings could be worked with in 1 h. After the splicing and grafting process had been completed, the survival rate of the grafted seedlings was 85%. The simple device structure could be used by the industry to assist operators in clipping and cutting seedlings, reduce the complexity of grafting operations, shorten training times, address the problem of labor constraints in Taiwan’s agricultural industry, and improve product quality and efficiency.