Nucleic acid amplification tests have been widely used in clinical diagnostics, food safety monitoring, and molecular biology. Loop-mediated isothermal amplification (LAMP) is a prevailing nucleic acid isothermal amplification method. It has become a powerful alternative to conventional polymerase chain reaction (PCR) for pathogen detection because of its simplicity, rapidity, and high sensitivity. However, the current LAMP methods, especially LAMP with two loop primers, suffer from undesired nonspecific amplification with strong background signals due to the increasing target sites. This nonspecific amplification substantially reduced the reliability of LAMP and limited its applications in clinical diagnostics. Here, we report a "dual-priming" ("self-priming" and "pairing-priming") isothermal amplification (DAMP) assay for rapid nucleic acid detection with ultralow nonspecific signals. This method takes advantage of the "dual-priming" strand extension strategy by adding two pairing-competition primers and designing unique inner primers, enabling highly sensitive and specific molecular detection. As an application demonstration, the DAMP assay was used to detect HIV-1 DNA/RNA and Escherichia coli DNA, showing equal or better sensitivity with shorter detection time compared to conventional LAMP and PCR methods. More importantly, the DAMP assay showed ultralow background signals without false positive signals even after a 2 h incubation. Such a simple, reliable, sensitive, and specific DAMP assay can be well suited for rapid nucleic acid detection as point-of-care testing, particularly in resource-limited settings.