It has been an urgent need for developing a new bright long-wave emitting phosphor to improve the color rendering index (CRI) of white light-emitting diodes (WLEDs). Here, based on the concept of oxygen vacancy-induced long-wave emission by Bi3+ doping, we selected BaSrGa4O8 as the matrix, which has a low-dimensional chain structure that can produce enough oxygen vacancies. After the introduction of Bi3+, orange emission was successfully achieved. To further improve the luminescence efficiency, the system of BaSrGa4O8:Bi3+,K+ was designed. Interestingly, although significant emission enhancement was obtained, the material showed reduced absorption with increased oxygen vacancies. More detailed experimental evidences confirm that oxygen vacancies can activate Bi3+ to achieve long-wave emission. Our results provide a new way to design Bi3+-based long-wave emitting phosphors with low-dimensional crystal structure. Finally, a WLED device containing BaSrGa4O8:Bi3+,K+ was fabricated and exhibited an enhanced CRI, which shows a promising application in WLEDs.