Two field experiments were conducted during 2017-2018 and 2018-2019, at the Experimental Farm, Faculty of Agriculture, Suez Canal University, Ismailia, Egypt with aim of investigation of potassium application on earliness of potato. To achieve this goal, five different net potassium levels: 0, 60, 90, 120, and 150 kg/Feddan were applied and potato tubers were harvested at two harvesting times: 90 and 105 days after planation. The results reported that both potassium application and harvesting time as well as their interaction significantly affected most of the studied traits. The highest values of plant height, plant fresh weight, plant dry matter, tuber dry matter, marketable yield/feddan, total yield/feddan, soluble solid content (SSC), nitrogen (N) content  and potassium (K) content  were obtained from the plants received 120 kg K and harvested at 105 days after planation. While, the potassium fertilized plant at 120 kg/feddan and harvested at 90 days achieved the maximum values of total yield per plant, total sugar and non-reducing sugars. However, the difference between these two treatments was not necessarily significant for some traits. In addition, the results of the current study interestingly clarified that potassium level (150 kg) negatively affected some yield attributes in both harvesting times compared to the other potassium levels. Consequently, the result of the current study indicates that high level of potassium (120 kg) can hasten the earliness of potato, which may achieve notable financial profits for potato growers.