Sweet cherry (Prunus avium L.) stems in the form of infusions and decoctions are traditionally consumed for diuretic and anti-inflammatory purposes. This study aimed to evaluate antimicrobial and antibiofilm activity of ethanolic and methanolic extract made from sweet cherry stems. Extracts are obtained by the Soxhlet extraction and maceration procedures. For the determination of the minimum inhibitory concentration, the broth microdilution method is employed, and the assessment of the microbiocidal activity of the extracts is conducted. The antibiofilm activity was tested through the tissue culture plate method, which also allowed the determination of the biofilm-forming categories of investigated strains. The final step involved the calculation of the biofilm inhibition percentage. Examined extracts with the balanced activity inhibited the growth of all microorganisms, with Gram-negative bacteria being more sensitive in comparison to Gram-positive. The values of the minimum inhibitory concentration were 125 µg/ml, and 250 µg/ml, respectfully. Candida albicans was the most susceptible and the minimum inhibitory concentration of both extracts was 62.50 µg/ml. The microbiocidal activity of the extracts was not recorded. Extracts exhibited different impacts on the biofilm-forming capacity of the investigated microbes, and both inhibition and stimulation effects are noted. The percentage of the biofilm inhibition was from 14.27% to 84.78%, with the highest inhibition recorded for the multidrug-resistant Escherichia coli, treated with the ethanolic extract. Sweet cherry stems are a valuable source of natural bioactive compounds, but their usage in the treatment of microbial infections should be correctly and carefully implemented.