Pengolahan water kefir masih terbatas dan belum banyak dikenal masyarakat. Semangka memiliki kadar air dan kandungan gizi yang tinggi, namun dalam pembuatan water kefir semangka diperlukan penambahan sukrosa untuk memenuhi nutrisi bagi pertumbuhan mikroorganisme. Pengolahan water kefir semangka merupakan upaya pengembangan pengolahan water kefir serta untuk meningkatkan nilai fungsional semangka. Penelitian ini bertujuan untuk mengetahui pengaruh penambahan sukrosa dengan konsentrasi yang berbeda terhadap total BAL, total padatan terlarut, total asam, CO2, dan organoleptik water kefir semangka. Rancangan percobaan yang digunakan adalah Rancangan Acak Lengkap (RAL) dengan 5 perlakuan (kontrol, sukrosa 3%, sukrosa 6%, sukrosa 9%, sukrosa 12%) dan 4 ulangan. Data hasil pengujian total padatan terlarut, total asam, CO2, total BAL dianalisis menggunakan Analysis of Variance (ANOVA) pada taraf signifikansi 5% dan dilanjutkan dengan Duncan’s Multiple Range Test (DMRT) apabila berpengaruh nyata. Data hasil pengujian sifat sensoris dianalisis dengan Kruskal Wallis pada taraf signifikansi 5% dan dilanjutkan dengan Mann Whitney U Test apabila berpengaruh nyata. Hasil yang diperoleh menunjukkan bahwa penambahan sukrosa dengan konsentrasi berbeda berpengaruh nyata (p<0.05) terhadap total BAL, total padatan terlarut, total asam, dan CO2 water kefir semangka. Hasil uji sensoris metode rangking menunjukkan bahwa penambahan sukrosa dengan konsentrasi yang berbeda berpengaruh nyata terhadap rasa, warna, dan sensasi soda, namun tidak berpengaruh nyata terhadap atribut aroma. Water kefir semangka dengan perlakuan penambahan sukrosa 9% merupakan perlakuan terbaik untuk parameter yang diuji secara menyeluruh. Water kefir processing is still limited and not yet widely known to the public. Watermelon has a high water content and nutrient content, but in making water kefir watermelon, it is necessary to add sucrose to fulfil the nutrients for the growth of microorganisms. The processing of watermelon water kefir is an effort to develop water kefir processing and to increase the functional value of watermelon.This study aims to determine the effect of adding sucrose with different concentrations of total lactic acid bacteria (LAB), total dissolved solids, total acid, CO2, and organoleptic values of water kefir from watermelon fruit. The experimental design used was a Completely Randomized Design (CRD) with 5 treatments (control, sucrose 3%, sucrose 6%, sucrose 9%, sucrose 12%) and 4 replications. The obtained data from total dissolved solid, total acid, CO2, and total lactic acid bacteria (LAB) were analyzed using Analysis of Variance (ANOVA) at the 5% significance level and continued with the Duncan Multiple Range Test (DMRT) if it had a significant effect. The obtained data from sensory properties were analyzed using Kruskal Wallis at the 5% significant level and continued with the Mann Whitney U Test if it had a significant effect. The results obtained showed that the addition of sucrose with different concentrations had a significant effect (p <0.05) on total dissolved solids, total acid, CO2 and total LAB water kefir watermelon. The sensory test results of the ranking method showed that the addition of sucrose with different concentrations significantly affected the taste, color, and sensation of soda, but did not significantly affect the aroma of water kefir watermelon. Water kefir watermelon with the treatment of adding sucrose 9% was the best treatment for parameters tested thoroughly.