Potato is an important food and cash crop which in Ethiopia is produced two or more times in a year. However, its productivity is low owing to a number of constraints including a) limited availability of quality planting materials, and b) poor tuber sprouting due to long dormancy period of improved varieties at the time of planting. Two consecutive experiments were conducted from November 2013 to June 2014: 1) to assess the effects of gibberellic acid (GA3) and storage methods on seed tuber dormancy breakage of two potato varieties; and 2) to assess the effects of dormancy breakage treatments and storage methods on subsequent growth, yield and related traits of potato crop. The treatments in the first experiment consisted of two potato varieties (Bubu and Bate), three levels of GA3 [0, 10 and 20 parts per million (ppm)], and three storage methods [in diffused light store (DLS), in pit store (PS), and in farm-yard manure (FYM)]. The first trial was laid out as a complete randomized design with four replications and conducted at Haramaya University, Ethiopia. The second trial consisted of seed from each treatment in the first experiment, planted in randomized complete block design with three replications on a farmers’ field. The results showed that varieties, application of GA3 and storage methods as well as the interaction among the variety and treatments significantly affected tuber dormancy period, sprouting characteristics and subsequent tuber yield. When tubers were treated with 20 ppm GA3 and stored under FYM, the dormancy period was reduced from 102.5 and 52 to 36.5 and 31 days in improved and farmer’s variety, respectively. Tuber treatment with 20 ppm GA3 and stored under DLS, PS, and FYM, increased marketable tuber yield by 31.6%, 29.6%, and 33.6%, respectively for Bubu variety and by 92.5%, 78.4%, and 80.9% for Bate variety, respectively compared to non-GA3 treated tubers stored under DLS, PS, and FYM. However, tubers of improved variety Bubu treated with 20 ppm GA3 and stored under DLS produced the highest marketable tuber yield of 34.20 ton per ha. Tuber quality attributes (specific gravity, dry matter, and total starch content) were affected only due to interaction effects of variety and GA3 application with the highest values at 20 ppm GA3 for improved potato variety Bubu. In general, the research indicated that treating seed tubers with GA3 and storing under DLS, PS or FYM promoted early tuber sprouting and better tuber yield of both varieties. These results suggest that, use of GA3 treatment combined with different storage methods enhances early tuber sprouting and increases tuber yield. Nevertheless, further research should be continued to evaluate different potato varieties, GA3 treatment, and storage methods under different atmospheric conditions and production seasons.