Introduction: In several European mountain chains, the expansion of the tall shrub Alnus viridis into mountain pastures has altered vegetation structure and composition, reduced plant species diversity, and diminished forage quality. Recent woody encroachment research has explored the use of robust livestock breeds, such as Highland cattle (Bos taurus taurus), as a potential agroecological restoration tool to reduce A. viridis encroachment. However, empirical evidence on their medium-term (5 years) impact on shrub cover remains limited. Objectives: To address this gap, we evaluated over 5 years how different grazing pressures of Highland cattle impacted A. viridis shrubland structure. Methods: A field experiment was conducted in A. viridis-encroached pastures, where three paddocks were grazed over five consecutive summer seasons. For 344 A. viridis shrubs, we classified shrub position (border vs. interior of the shrubland), measured their basal diameter and proportion of dead trunks, the understory light availability, and the proportion of trunks with resprouts. Each year, 8–10 cows (approximately 400 kg on average) were equipped with Global Positioning System collars, and cattle stocking density was calculated within a 10 m buffer around each shrub. Results: The increase in livestock density led to a significant increase in trunk mortality and understory light availability, particularly at the shrubland edges. The number of resprouts also increased with higher stocking densities. Conclusions: Our findings show that Highland cattle browsing reduces A. viridis cover and increases understory light availability, promoting favorable conditions for grassland restoration. Nevertheless, the resprouting response of A. viridis indicates that a 5-year grazing period is insufficient to control A. viridis encroachment at the plot scale.