Porcine epidemic diarrhea virus (PEDV) and porcine circovirus type 2 (PCV2) are both important global pathogenic viruses which have a significant impact on the swine industry. In this study, a duplex loop-mediated isothermal amplification (duplex LAMP) method was developed in combination with lateral flow dipstick (LFD) for simultaneous detection of PEDV and PCV2 using specific sets of primers and probes designed based on the conserved regions of a spike gene (KF272920) and an ORF gene (EF493839), respectively. The limit of detection (LOD) values of the duplex LAMP-LFD for the detection of PEDV and PCV2 were 0.1 ng/µL and 0.246 ng/µL, respectively. The LOD of duplex LAMP-LFD was 10-times more sensitive than conventional PCR and RT-PCR-agarose gel-electrophoresis (PCR-AGE and RT-PCR-AGE). No cross-reaction to each other and to other pathogenic viruses that can infect pigs were observed according to analytical specificity tests. The duplex LAMP-LFD method for the simultaneous detection of PEDV and PCV2 co-infection could be completed within approximately 1.5 h, and only a simple heating block was required for isothermal amplification. The preliminary validation using 50 swine clinical samples with positive and negative PEDV and/or PCV2 revealed that the sensitivity, specificity, and accuracy of duplex LAMP-LFD were all 100% in comparison to conventional PCR and RT-PCR. Hence, this study suggests that duplex LAMP-LFD is a promising tool for the early detection and initial screening of PEDV and PCV2, which could be beneficial for prevention, planning, and epidemiological surveys of these diseases.