Watermelon is an important horticultural crop which is grown in warm climate worldwide. However, its production and productivity is low owing to lack of high yielding improved varieties and poor knowledge of using mulches. Therefore, a field experiment was conducted in west Dembia district under irrigation from January to April 2021 to investigate the effect of mulches on growth and fruit yield of watermelon varieties. Factorial combinations of two varieties of watermelon (Crimson Sweet and Sugar Baby) and four types of mulches (black plastic, white plastic, grass mulch and no mulch as control) were arranged in a randomized complete block design with three replications. The remaining necessary agronomic practices and crop management activities were undertaken uniformly. The data presented under this dataset article includes phenological parameters (i.e. Days to 50 % germination, Days to 50 % flowering, and Days to 50 % maturity), growth parameters (i.e. main vine length, number of lateral branches per vine, number of nodes on main vine, and number of leaves on the main vine) and yield and yield component parameters (i.e. Number of total fruit plant-1 , number of marketable fruit plant-1 ,number of unmarketable fruit plant-1 , fruit length, fruit diameter, average fruit weight, marketable fruit yield, unmarketable fruit yield and total fruit yield). All the collected data were subjected to analysis of variance (ANOVA) and the analysis was car- ried out using the SAS version 9.4 software computer pro- gram's General Linear Model (GLM) procedure [1]. As de- scribed in Montgomery [2], the residuals were examined to verify the normal distribution and homogeneous variance model assumptions on the error terms for each response variable. Because the eight treatment combinations were ran- domized within each block, the independence assumption is valid. When a treatment effect was significant, multiple means comparison was performed at a 5 % level of signif- icance using the least significant difference (Fisher's LSD) method to generate letter groupings and correlation analy- sis was performed using the Pearson correlation procedure found in SAS. This dataset article, therefore gives information about the effects mulching on productivity of watermelon va- rieties. Additionally, it provides the appropriate and econom- ically feasible type of mulching material for maximized fruit yield of watermelon varieties in the study area or other areas having similar agro ecology. Hence, this information can al- low other researchers to review the supplement data, meth- ods, and make detailed analysis, which possibly giving rise to new lines of inquiry. This can also give rise to new collabo- rations and boost the reputation of the present research data within the scientific community and to make it available to everyone around the subject matter to use as they wish. (c) 2024 The Author(s). Published by Elsevier Inc. This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/4.0/)