This study presents an assembly-free ball lens structure at the tip of tapered multimode optical fiber to enhance the light collection efficiency for pH measurements. A 35 µm diameter ball lens was fabricated at the sensor tip. In addition, a thin layer of fluorescence dye was mixed with sol-gel that formed at the fiber tip for pH sensing. The simulation result demonstrates the light propagation on the ball lens tip. The experiment results reveal that the proposed sensor has a rapid response time (< 3 seconds), high sensitivity, and pinpoint accuracy (±1.0%) in the pH range of 6.0-8.0