BACKGROUND: In the initial phases of the COVID-19 pandemic, strategies adopted to reduce the dissemination of SARS-CoV-2 relied on non-pharmacological interventions, including physical distancing. Mobility restrictions affected the availability and quality of care for many health conditions, including sexually transmitted infections. OBJECTIVE: To investigate the impact of the COVID-19 pandemic mobility restriction on syphilis and HIV testing in outpatient settings. METHODS: In this study, we collected the weekly number of syphilis and HIV tests performed in a referent laboratory in São Paulo, Brazil, as well as the percentage of positive tests between January 2019 and December 2021. We also retrieved data on retail and recreation mobility in São Paulo city using Google COVID-19 Community Mobility Reports. We explored the association between populational mobility and the number of weekly tests and the association between the number of weekly tests and the percentage of positive results during the pandemic period. The analyses were conducted separately for syphilis and HIV tests. RESULTS: We found that mobility restrictions during the COVID-19 pandemic have been associated with a significant decrease in both syphilis and HIV tests performed in outpatient settings. We also observed that the number of tests performed was inversely associated with the percentage of positive results for syphilis; this association was also apparent for HIV tests in the first wave of the pandemic in the graphic analysis. CONCLUSION: Taken together, our findings suggest an indirect impact of COVID-19 pandemic-related mobility restrictions on the uptake of diagnostic tests for HIV and syphilis and the potential adoption of targeted-testing strategies. Understanding the extent and complexity of COVID-19 aftermaths on specific conditions and communities is essential to build strategies to mitigate the long-term consequences of COVID-19.