Background: Dental phobia significantly impairs treatment adherence and oral health–related quality of life. While intravenous sedation (IVS) is commonly used to manage anxiety, interest in non-pharmacological alternatives is increasing. Visual color stimuli are known to affect emotional processing and autonomic nervous system activity. This study investigated whether brief exposure to colored goggles (translucent, green, blue, red) influenced physiological and psychological stress markers in patients with dental phobia undergoing IVS. Methods: Twenty patients with dental phobia (CMDAS ≥ 20) participated in a within-subject repeated measures design, experiencing all four color conditions in randomized order via Latin square. Salivary alpha-amylase (sAA), heart rate (HR), and Visual Analog Scale (VAS) scores for pain and satisfaction were measured at four time points. The Friedman test, followed by Wilcoxon signed-rank tests with Bonferroni correction, was used to compare conditions. Results: Prior to peripheral intravenous cannulation (PIC), green goggle exposure significantly reduced median sAA levels compared to the translucent control (p = 0.009). HR was lower in the green and blue conditions than in the red, although not significantly. VAS pain scores were significantly reduced under green and blue conditions; satisfaction scores remained uniformly high across all conditions. Red did not worsen stress responses compared to the control and may promote increased engagement. Conclusions: Cool color stimuli—particularly green and blue—may attenuate acute stress responses in patients with dental phobia prior to PIC. Incorporating such visual cues into preoperative environments may serve as a simple, non-invasive adjunct to managing dental anxiety.