This paper presents the fabrication of nanochannels using glancing angle deposition (GLAD) with line seeds. GLAD is a bottom-up nanofabrication technique that creates nanometer-level features by the ballistic shadowing effect at oblique incident angles in physical vapor deposition (PVD) processes. GLAD exhibits the unique advantage to create 3D nanofeatures such as nanocolumns, helices, chevrons, and combinations, comparing to top-down nanonamufacturing techniques. Advanced seeding schemes allow GLAD to produce ordered nanostructure arrays. In this paper, we focus on studying the design rules of line seeds for GLAD, and the potential for creating nanochannels using GLAD nanoribbons grown from the line seeds. Unlike traditional one-dimensional (1D) point seeds, the cross-sectional profiles of line seeds have an important impact on the size and morphology of the nanoribbons. We demonstrated that line seeds with circular cross-sections and micrometer widths created from conventional photolithography can be used for creating ribbons with width less than 300 nm. The centimeter-long nanoribbons are used as nanotemplates for nanochannels. The process is compatible with various materials such as parylene C and silicon dioxide as the capping material, and rigid/flexible substrate choices for the nanochannels as well. The nanochannels created by GLAD with line seeds can potentially be used in nanofluidics, biological, and sensing applications.