A two-years (2016/2017 and 2017/2018) field experiments were carried out at Experimental Farm, Agriculture Faculty, Zagazig University, Egypt to evaluate yield components, potassium content and some competitive indices between caraway and onion at different ridge ratios (sole crop of each components, 1:1, 1:2 and 2:2 of caraway: onion, respectively) under different potassium fertilization rates (0.0, 25 and 50 kg K2O/fad. A split-plot experiment based on randomized complete block design with three replications was planned. Results indicated that yield components (different grades of yield and exportable, marketable and total yield of onion as well as umbel number/plant, fruit and oil yield/plant and /faddan of caraway), potassium content/plant of each crop and competitive indices between them were affected by experimental factors. In most cases, onion sole crop recorded the highest values in yield components compared to intercropping systems under all potassium fertilization rates. In the same trend, the highest value in each of fruit and volatile oil yield /faddan of caraway was recorded with sole caraway crop. Also, the highest rate of potassium recorded significant increase in these parameters compared to control. Competition indices, i.e., land equivalent ratio (LER), area time equivalent ratio (ATER), land utilization efficiency (LUE%) and relative crowding coefficient (RCC) revealed that, applied intercropping system (1:2) was more efficient than sole cropping and other ones under study when combined with potassium fertilization rate at 50 kg K2O/faddan, in most cases. Aggressivity (A) estimation indicated that caraway was dominant while onion was dominated. Generally, this mixture seems promising in the development of sustainable crop yield advantages with a limited use of external inputs under Sharkia Governorate conditions.