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Funding Information: This work was supported by Business Finland corona-co-creation funding for the project Antiviral Fibers?pilot with extracts from Finnish forests (grant: 40699/31/2020). This study was also funded by the Natural Resources Institute Finland?s strategic research funding to the projects ?More, faster, higher quality: potential of short-rotation aspen and willow biomass for novel products in bioeconomy? (AspenWill) and ?Added value potential of new and under-utilized fibre sources in Finnish value networks of green bioeconomy: prefeasibility, prototyping, and market acceptance? (VALUEPOT). In addition, Academy of Finland has supported this study via the project ?Antivirals from Forest Biomasses: Structure, Function, and Applicability? (grant: 342250). Work was also funded by Jane and Aatos Erkko Foundation: Novel probes for discovering antivirals. Publisher Copyright: Copyright © 2021 Tienaho, Reshamwala, Sarjala, Kilpeläinen, Liimatainen, Dou, Viherä-Aarnio, Linnakoski, Marjomäki and Jyske. Earlier studies have shown that the bark of Salix L. species (Salicaceae family) is rich in extractives, such as diverse bioactive phenolic compounds. However, we lack knowledge on the bioactive properties of the bark of willow species and clones adapted to the harsh climate conditions of the cool temperate zone. Therefore, the present study aimed to obtain information on the functional profiles of northern willow clones for the use of value-added bioactive solutions. Of the 16 willow clones studied here, 12 were examples of widely distributed native Finnish willow species, including dark-leaved willow (S. myrsinifolia Salisb.) and tea-leaved willow (S. phylicifolia L.) (3 + 4 clones, respectively) and their natural and artificial hybrids (3 + 2 clones, respectively). The four remaining clones were commercial willow varieties from the Swedish willow breeding program. Hot water extraction of bark under mild conditions was carried out. Bioactivity assays were used to screen antiviral, antibacterial, antifungal,yeasticidal, and antioxidant activities, as well as the total phenolic content of the extracts. Additionally, we introduce a fast and less labor-intensive steam-debarking method for Salix spp. feedstocks. Clonal variation was observed in the antioxidant properties of the bark extracts of the 16 Salix spp. clones. High antiviral activity against a non-enveloped enterovirus, coxsackievirus A9, was found, with no marked differences in efficacy between the native clones. All the clones also showed antibacterial activity against Staphylococcus aureus and Escherichia coli, whereas no antifungal (Aspergillus brasiliensis) or yeasticidal (Candida albicans) efficacy was detected. When grouping the clone extract results into Salix myrsinifolia, Salix phylicifolia, native hybrid, artificial hybrid, and commercial clones, there was a significant difference in the activities between S. phylicifolia clone extracts and commercial clone extracts in the favor of S. phylicifolia in the antibacterial and antioxidant tests. In some antioxidant tests, S. phylicifolia clone extracts were also significantly more active than artificial clone extracts. Additionally, S. myrsinifolia clone extracts showed significantly higher activities in some antioxidant tests than commercial clone extracts and artificial clone extracts. Nevertheless, the bark extracts of native Finnish willow clones showed high bioactivity. The obtained knowledge paves the way towards developing high value-added biochemicals and other functional solutions based on willow biorefinery approaches.