This study presents a smartphone-integrated paper-microfluidic (SiPM) platform that enables accurate diagnosis of urinary tract infections (UTIs) by directly identifying white blood cells (WBCs) in real human urine samples on a smartphone. The SiPM system is a fully integrated platform, mainly consisting of a paper-based microfluidic filter and a smartphone-integrated fluorescence microscope. The paper-based filtration device allows a low-cost, simple method for dying and isolating target WBCs in urine using capillary action through paper layers with several different pore sizes without extra pumps and tubes typically required for fluidic actuation in conventional microfluidic devices. An integrated smartphone is used for fluorescence imaging and microscopic analysis of the stained WBCs to provide rapid diagnostic results at the point of care without the need of expensive laboratory equipment and specialized training. The fabrication process for the system is cost- effective and simple, enabling more practical applications for resource-limited settings, compared to other point-of-care microfluidic devices that quantify bacterial concentrations. We have experimentally demonstrated the capabilities of SiPM for isolation of target WBCs (more than 95%) in a urine solution using the paper microfluidic filter, the effectiveness of the smartphone microscope with 14.4× magnification to obtain clear images of urine solutions, the reliability of the platform’s to detect UTI through cell counting of various urine concentrations with 100% specificity and 96.67% sensitivity validated by hemocytometer measurements, and successful differentiation between real UTI patient and healthy person urine samples. The entire measurement process from filtration to quantification of real human urine samples was rapidly completed within 10 minutes, showing its potential for POC applications. The fully integrated SiPM system provides a low-cost, rapid, and portable UTI diagnostic tool that can improve the access of accurate test results to developing areas and thus reduce suffering by speeding up therapy timelines.