Bovine mastitis is an inflammatory condition of the mammary gland that induces physical, chemical, and bacteriological alterations in milk, as well as structural changes in mammary tissue. These impacts highlight the need for practical, viable, and cost-effective therapeutic alternatives. The objective of this exploratory, preliminary study was to assess the potential efficacy of a hydroalcoholic extract of Eucalyptus camaldulensis as an alternative antimicrobial treatment for bovine mastitis. The sample consisted of 40 quarters with mastitis corresponding to 10 lactating cows, divided into two groups of 20 quarters in the control group (5 cows) and 20 (5 cows) for the group treated with the application of three intramammary doses of the E. camaldulensis extract. California Mastitis Test (CMT) reactions showed no statistically significant differences between the control and treatment groups, either before or 48 hours after the third administration (OR = 0.63; 95% CI: 0.11–3.70; p = 0.610). Evaluation of the antimicrobial activity of E. camaldulensis extract demonstrated a significant reduction (p < 0.001) in bacterial load 24 hours after the third intramammary application. This effect was not observed in the control group (p ≥ 0.05), as determined by the marginal means test of the mixed-effects model. Based on the preliminary findings of this pilot study, the Eucalyptus camaldulensis extract shows potential as an alternative antimicrobial agent in cases of bovine mastitis; nevertheless, larger scale studies are needed to substantiate its clinical effectiveness.