Availability of a rapid and sensitive diagnostic technique is key in successful prevention and control of infectious diseases like foot-and-mouth disease (FMD). Existing conventional diagnostic tests for FMD are laborious and time-consuming with low sensitivity and specificity. Molecular-based techniques are costly and difficult, involving refined apparatus like a thermal cycler. In the present study, the technique of real-time loop-mediated isothermal amplification (RT-LAMP) was standardized for diagnosing FMDV and its serotypes, evaluated using field samples, and compared with the existing real-time PCR in Pakistan. RT-LAMP amplified the target 3D gene using specific primers at 65 °C for 60 min and the VP1 gene using serotype specific primers at 63 °C for 60 min. A total of 38 samples out of 50 were positive by RT-LAMP and identified serotypes were A (n = 15), O (n = 15), and Asia-1 (n = 8). The efficiency of RT-LAMP in this study was highest for serotype Asia-1 (80.9%) followed by serotype A (73.4%) and O (62.35).