Worldwide yarn diversity in terms of structure and properties has increased in recent years. Especially composite yarns produced by multiple components have become very preferable in both weaving and knitting sectors. Among these yarns, core and dual core-spun yarn are more prominent in some areas due to their particular performance. In this study, the structure and properties of plain, elastane cored, and elastane + filament cored composite yarns, which were spun by using cotton as sheath fibers, are comparatively investigated. With a constant Ne 16/1 linear density, a carded yarn production line with modified ring-spinning system was used to produce the composite samples using 5.56% elastane ratio for both and 13.79% polybutylene terephthalate (PBT) ratio for dual core. It was observed that the strength of the composite yarns decreased, while the elongation values at the time of breaking tended to increase. There was some deterioration in transition from plain yarn to dual core composite yarn in terms of unevenness and yarn defects, while some improvement was observed in terms of yarn hairiness. In order to dwell on the causes of this situation, the surface and cross-sectional images of the yarns were also studied.