Meadowsweet (Filipendula ulmaria (L.) Maxim) is Rosaceae family perennial herb. Traditional uses of F. ulmaria include inflammatory problems like rheumatism, arthrosis, and arthritis), gastrointestinal disorders, liver malfunction, and gout. The pharmaceutical industry has been very interested in this plant because of its health benefits. The presence of phenolic secondary metabolites is thought to be the primary cause of meadowsweet's biological activity and therapeutic efficacy. This study was intended to compare and evaluate the biological activities (antibacterial, antioxidant, antitumor and toxicity) and phenolic profiles (total phenol-flavonoid content and individual phenolic constituents) of F. ulmaria aerial parts obtained from two different sources (naturally- and in vitro-grown). Antibacterial activity was evaluated using 17 different bacteria (10 human and 7 fish pathogens) with disc diffusion method. Methanolic extracts of in vitro-grown parts showed higher antibacterial effect than naturally-grown parts with all tested bacterial pathogens (human and fish). On the other hand, other extracts (aqueous, ethanol, hexane, and ethyl acetate) demonstrated higher antibacterial potential with field-grown parts. The highest sensitivity was observed with Staphylococcus epidermidis, S. aureus and Enterobacter cloacae to aqueous extract of field-grown plants. The potent antibacterial activity of F. ulmaria extracts rendered the Agrobacterium tumefaciens-induced potato disc tumor assay inapplicable. Toxicity assay (brine shrimp) showed that aqueous extract of both sources had the lowest toxicity. Methanolic extract of both parts had a strong antioxidant potential (DPPH radical scavenging activty) having IC50 values as 205.65 µg/mL and 206.74 µg/mL, respectively, and similar level of overall total phenol-flavonoid contents. Individual phenolic analysis with HPLC-DAD showed that the most prevalent phenol was rutin in both sources. While the quantities of chlorogenic acid in both aerial parts were similar, the parts that were grown naturally had higher levels of salicylic acid and rutin. These findings demonstrated the effective antibacterial and antioxidant properties, high phenolic content, and low toxicity of both F. ulmaria sources, indicating that they can be utilized in nutraceutical industry due to their high health promoting potential.