Hydrogel fibers have drawn a great deal of attention during the past few years for a wide range of applications, spanning from tissue engineering to biosensing. Here, we present a double-coaxial flow microfluidic device to assemble fiber-shaped, meter-long fibers consisting of a hydrogel core and an alginate shell. Various hydrogel fibers from collagen type I, GelMA, NiPAM, and agarose have been fabricated with this approach. These fibers were mechanically characterized exhibiting Yong's moduli between ∼10 to ∼200 kPa, making them mechanically suitable for tissue engineering applications. Moreover, we encapsulated human mesenchymal stem cells (MSCs) in collagen fibers and observed proliferation and spreading after 7 days of culture indicating the biocompatibility of the process. The fiber-shaped structures we fabricated can be potentially used for creating three dimensional tissue constructs, wound patches, and flexible biosensors.