Two new biflavonoids, 2″-hydroxygenkwanol A (1) and 4′-methylgenkwanol A (2), together with fourteen known compounds were isolated from the aerial parts of Daphne linearifolia Hart. Their chemical structures were elucidated by extensive NMR spectral studies, as well as by ESI-MS analysis. The affinity of all compounds towards Hsp90, one of the most promising targets for the modern anti-cancer therapy, by surface plasmon resonance was tested. Achieved results demonstrated that 1 efficiently interacts with the protein, also allowing some structure–activity relationship evaluations.