Textile-based sensors have a broad application potential in technical textiles, e.g., for measuring temperature, strain, humidity, pressure, etc. Moreover, textile-based sensors represent a promising class of sensor technologies that open up new possibilities for applications in health monitoring, sports, wearables, and smart clothing by integrating sensor technology into textiles. These sensors utilize flexible and stretchable materials to enable their seamless integration into garments, allowing them to be worn comfortably and unobtrusively. Their appeal lies in their breathability, stretchability, flexibility, and comfortable feel, along with an easier fabrication process compared to traditional rigid sensors. The growing importance of flexible, thin, and lightweight sensors in electronic wearables is increasingly being researched, which is reflected in the growing number of publications. By using different fibres and coatings, textile-based sensors can detect a variety of physiological parameters such as heart rate, respiratory rate, muscle activity, and posture. In general, the integration of textile-based sensors into technical textiles allows for the creation of intelligent and functional materials that offer a wide range of applications. This incorporation is critical for the functionality of products, enabling them to sense, respond, and adapt to external stimuli. The evergrowing demand for smart textiles creates an increase in expectations for the range, accuracy, and stability of sensor measurements. The properties of both the textile and conductive components, alongside the level of mechanical impact that they are subjected to during use, significantly influence the overall reliability and durability of the electronic textiles. So far, only few solutions have passed durability tests, which has resulted in products that appear promising for marketable product solutions. This article gives an overview of the current research on textile-based sensors for various applications in technical textiles and smart clothing, as well as the materials and fabrication techniques used. Furthermore, it addresses challenges in sensor performance and future advancements in materials and technologies.