This paper reviews the current state-of-the-art development of single-molecule detection (SMD)-based methods for ultrasensitive and specific analysis of genomic sequences. We first discuss several newly devised single fluorescent probe strategies that allow separation-free detection of low-abundance DNA sequences, such as quantum dot (QD)-mediated fluorescence resonance energy transfer (FRET) technology and dual-color fluorescence coincidence and colocalization analysis. Various schemes toward single DNA sizing and sequencing in solutions or on surfaces are also reviewed. In the end, we summarize the different microfluidic approaches developed for use with SMD to facilitate rapid, low-volume and quantitative analysis, such as electrokinetic and hydrodynamic single-molecule manipulation techniques.