Due to the important roles of resistance training and protein consumption in the prevention and treatment of sarcopenia, we assessed the efficacy of post-exercise Icelandic yogurt consumption on lean mass, strength, and skeletal muscle regulatory factors in healthy untrained older males. Thirty healthy untrained older males (age = 68 ± 4 yr) were randomly assigned to Icelandic yogurt (IR; n =15, 18 g of protein) or an iso-energetic placebo (PR; n =15, 0 g protein) immediately following resistance training (3x/week) for eight weeks. Before and after training, lean mass, strength, and skeletal muscle regulatory factors (insulin-like growth factor-1 [IGF-1], transforming growth factor-beta 1 [TGF-β1], growth differentiation factor 15 [GDF15], Activin A, myostatin [MST], and follistatin [FST]) were assessed. There were group x time interactions (p < 0.05) for body mass (IR: Δ 1, PR: Δ 0.7 kg), body mass index (IR: Δ 0.3, PR: Δ 0.2 kg∙m−2), lean mass (IR: Δ 1.3, PR: Δ 0.6 kg), bench press (IR: Δ 4, PR: 2.3 kg), leg press (IR: Δ 4.2, PR: Δ 2.5 kg), IGF-1 (IR: Δ 0.5, Δ PR: 0.1 ng∙mL−1), TGF-β (IR: Δ −0.2, PR: Δ −0.1 ng∙mL−1), GDF15 (IR: Δ −10.3, PR: Δ −4.8 pg∙mL−1), Activin A (IR: Δ −9.8, PR: Δ −2.9 pg∙mL−1), MST (IR: Δ −0.1, PR: Δ −0.04 ng∙mL−1), and FST (IR: Δ 0.09, PR: Δ 0.03 ng∙mL−1), with Icelandic yogurt consumption resulting in greater changes compared to placebo. The addition of Icelandic yogurt consumption to a resistance training program improved lean mass, strength, and altered skeletal muscle regulatory factors in healthy untrained older males compared to placebo. Therefore, Icelandic yogurt as a nutrient-dense source and cost-effective supplement enhances muscular gains mediated by resistance training and consequently may be used as a strategy for the prevention of sarcopenia.