The roots of Gentiana lutea L. are utilized in the preparation of various beverages and herbal remedies, serving as a traditional remedy for gastrointestinal ailments. The spasmolytic activity that could substantiate the traditional use of G. lutea root had not been investigated. The main objective goal of the study was to determine the validity of its use as a traditional remedy. The extraction of G. lutea root was performed using a 50% hydroethanolic solvent with three different extraction techniques: ultrasound-assisted extraction (UAE), heat-assisted extraction, and percolation. The spasmolytic activity was tested on isolated rat ileum. The mechanism of action was monitored using the models of spontaneous contractions and acetylcholine-, histamine-, CaCl2-, Bay K8644-, L-NAME-, ODQ-, apamin-, BaCl2-, charybdotoxin-, glibenclamide-, TRAM-34-, and quinine-modified contractions. UAE, having the best bioactivity, was further subjected to a liquid–liquid extraction fractionation. HPLC phytochemical analysis was performed for all tested extracts and fractions. Gentian root extracts were rich in secoiridoids, xanthones, and flavonoids. The UAE has shown better results on spontaneous contractions in comparison to its fractions, leading to the more detailed testing of its spasmolytic mechanism of activity. The extract’s activity is primarily mediated through intermediate conductance Ca2+-activated K+ channels, ATP-sensitive K+ channels, voltage-sensitive K+ channels, and mechanisms that activate Ca2+ channels. Overall, the G. lutea root shows great potential in the treatment of spasmodic gastrointestinal ailments.