Some scientific reports indicated that Tomatotone (4-Chlorophenoxy acetic acid (4-CPA) is one of the plant hormones that can be used to increase fruit setting and yield of tomato. The aim of the research is to evaluate the efficacy of 4-chlorophenoxy acetic acid at different plant population density. Field trials were therefore conducted during the rainy season of 2020 at two locations. The treatments consisted of three population density (22,222, 26,666 and 33,333) and four concentrations of 4-CPA (0, 50, 75 and 100 mgL-1 of distilled water). The experiment was laid out in a Complete Randomized Block Design and replicated three times. The data collected on yield and yield components were subjected to analysis of variance. The result showed that 4-CPA had a significant effect on fruit length, fruit weight, marketable fruit yield and total fruit yield. Plant population density was obtained also to have significantly influenced total fruit yield and marketable fruit yield. Based on the results of the study, it could be suggested that farmers in the areas of study can be advised to grow UC82B tomato and apply 4-CPA at a density of 22,222 plants ha-1 for higher yield of the crop during rainy season