To increase the potassium content in tobacco leaves and reduce the amount of chemical fertilizer applied, a screening method via selective medium combined with tobacco lectin was used to screen highly efficient potassium-solubilizing bacteria from tobacco rhizosphere, and the effects of one of the isolated strains on promoting tobacco growth and potassium absorption were evaluated through pot and field experiments. A total of 6 strains of potassium-solubilizing bacteria were obtained from tobacco rhizosphere, among which Pseudomonas sp. strain LK26 exhibited excellent plant growth-promoting traits. The pot experiment showed that LK26 strain could significantly increase the weight of tobacco leaves and roots, and increase the potassium content in tobacco rhizosphere soil and tobacco leaves. The field experiment showed that compared with uninoculated tobacco plants with 20% reduced potash fertilizer and uninoculated tobacco plants with unreduced potash fertilizer, those inoculated with LK26 with 20% reduced potash fertilizer showed 27.71% and 10.25% higher the available potassium content in tobacco rhizosphere soil, respectively; and 17.80% and 5.30% higher potassium content in the lower leaves, 40.59% and 24.48% higher potassium content in the middle leaves, and 15.69% and 5.36% higher potassium content in the upper leaves, respectively. A potentially ideal biological potassium fertilizer-producing strain for use in tobacco production was developed. Strain LK26 has potential for further research and application.