Background: The aim of this study was to (i) determine IMP3 protein expression in benign and malignant laryngeal lesions, (ii) compare its expression to Ki-67, p53, cyclin D1, and (iii) finally, to examine the prognostic power of IMP3 in squamous cell carcinomas of the larynx (LSSC). Methods: IMP3 protein expression was evaluated in 145 patients, including 62 LSCC, 45 dysplasia (25 with low and 20 with high-grade dysplasia), and 38 benign lesions (vocal cord polyps and nodules). Results: IMP3 was significantly higher expressed in LSCC compared to dysplasia and benign lesions (p < 0.001; p < 0.001, respectively). Similarly, higher expression patterns were observed for Ki-67 and p53, whereas cyclin D1 was equally distributed in all three lesions. IMP3 (p = 0.04) and Ki-67 (p = 0.02) expressions were significantly linked to neck node positivity, and IMP3 overexpression to worse disease-specific survival (p = 0.027). Conclusion: Since IMP3 showed significantly higher expression in laryngeal carcinomas, but not in high- or low-grade dysplasia, it serves as a useful marker to differentiate between invasive and noninvasive lesions. Higher IMP3 expression represented a significantly worse prognosticator for clinical outcomes of patients with squamous cell carcinoma of the larynx.