The popularity of rosemary has grown as a natural alternative over the synthetic supplements due to its potential health benefits. The rosemary plant has been utilized to preserve food due to its ability to prevent oxidation and microbial contamination. The reason for this study was to determine the phytochemical components and antimicrobial activity of rosemary essential oil (REO) and the effect of REO addition (0.5 and 0.7%) on the chemical, microbiological, and sensory properties of stirred-like yogurt (SLY) during 16 days of storage at 4 °C. The obtained data observed that REO exhibited antimicrobial action against Escherichia coli, Staphylococcus aureus, and Salmonella marcescens, as well as fungi (Aspergillus flavus) and yeasts (Candida albicans). Increased REO to 0.7% accelerated (p < 0.05) the development of lactic acid bacteria (LAB) in SLY (8.3 log cfu/g) and delayed yeast growth up to 12 days. Molds and coliforms were also not found in the SLY samples with REO. In comparison to control samples, sensory results showed that the addition of REO improves the overall acceptance of SLY (p < 0.05). In conclusion, the current study found that REO could be used as a natural preservative during the production of SLY to extend shelf-life and promote LAB development.