The performance and feasibility of a recent welding technique called Cold Metal transfer (CMT) welding technique for Cold-Formed Steel (CFS) welded sections is presented in this paper. The study focuses on understanding the behaviour of flare v-groove welds on back-to-back connected CFS sections subjected to longitudinal shear. A total of thirty lap shear specimens were fabricated and the parameters such as length of the weld and thickness of the weld were varied and tested under longitudinal loading. The weld geometry was observed under an optical microscope after polishing and chemical etching of the weld cross-section to determine the thickness of the weld for CMT flare v-groove welds. Based on the weld cross-section profiles, a set of calibrated welding parameters for 1.5mm CFS section is presented in the paper. The lap shear specimens failed in either transverse plate tearing of the individual cross-section or fracture of the weld at the weld contours. The test results show that AISI design standard yield over-conservative strength prediction and inaccurate failure modes for longitudinal flare v-groove welds. Therefore, a limiting ratio constituting of length of the weld, outstanding flange length, ultimate strength of parent material, and ultimate strength of wire electrode is proposed in the paper to accurately predict the failure mode. Additionally, a modified and reliable design equation is recommended to determine ultimate shear strength of CMT flare v-groove welds subjected to longitudinal loading. © 2023 Elsevier Ltd