Tea plants [Camellia sinensis (L.) O. Kuntze] are hyperaccumulators of fluoride (F), but excessive F will harm the photosynthesis and metabolic activities of tea plants. Potassium (K) is one of the essential macronutrients of tea plants, which can enhance the photosynthesis of tea plants and their stress resistance. However, there are fewer studies on K in the accumulation of F in tea plants. In this study, we set three K treatment concentrations of 0 mM, 5 mM, 10 mM and finally found that when the tea plants were treated with F, exogenously applied 5 mM K treatment increased chlorophyll content, photosynthesis, and antioxidant enzyme activity, and reduced the extent of cellular damage, where starch particles content was reduced and the interstices of the chloroplast grana layer were more compact. After K treatment, the F content of new shoots decreased, and the flow rate of absorption of K by roots under F treatment was significantly increased through the Non-invasive Micro-test Technology (NMT), and 5 mM K treatment could effectively stabilize the membrane potential of roots. In addition, after K treatment, the relative expression of the F exporter CsFEX in tea plants was significantly upregulated, while the stress resistance gene expression of CsHAKs in tea plants was downregulated. Above all, appropriate K application could effectively alleviate the hyperaccumulation and stress effects of F on tea plants.