Sexually Transmitted Infections (STIs) are an important and growing public health concern. Implementation of screening programmes and awareness campaigns are crucial to mitigate this problem. A university in the central region of Portugal has devised a health-promotion programme, named Protection+, specifically directed towards the sexual health of the university community. The present study aimed to evaluate the results of the different actions undertaken as part of the health-promotion programme during the 2023–2024 academic year. Chlamydia, gonorrhoea, trichomoniasis and infection with Mycoplasma genitalium were assessed through real-time polymerase chain reaction protocols. Syphilis, infection with HIV, HBV and HCV were assessed through immunological assays. The adherence to the health-promotion programme after the awareness campaigns was also evaluated. STIs have been diagnosed in 13.7% of the 475 screened participants. Chlamydia was the STI most frequently diagnosed (8.4%), followed by infection with M. genitalium (2.3%), T. pallidum (2.0%) and N. gonorrhoeae (1.1%). HIV, HBV and HCV were diagnosed in a residual number of cases, and T. vaginalis was not detected in any of the screened participants. At the time of diagnosis, more than half of the infected patients were asymptomatic. After the implementation of awareness campaigns, an increase in the adherence to STI screening was observed, with the expected simultaneous increase in STI diagnoses. The high prevalence of STIs, particularly chlamydia, in the university population, along with the asymptomatic nature of these infections, demonstrated the importance of STI screenings and the implementation of campaigns that raise awareness on the prevention and consequences of untreated STIs.