Psittacanthus calyculatusis a hemiparasitic plant of an arboreal species (e.g., forest, fruit trees). Its foliage has therapeutic potential; however, little is known about its fruits. In this study, the phytochemical profile and biological activities ofP. calyculatusfruits hosted byProsopis laevigataandQuercus deserticolawere evaluated. The fruits ofP. calyculatusfromP. laevigatashowed the highest content of total phenols (71.396 ± 0.676 mg GAE/g DW). The highest content of flavonoids and anthocyanins was presented in those fromQ. deserticola(14.232 ± 0.772 mg QE/g DW; 2.431 ± 0.020 mg C3GE/g DW). The anthocyanin cyanidin-3-glucoside was detected and quantified via high-performance thin-layer chromatography (HPTLC) (306.682 ± 11.804 mg C3GE/g DW). Acidified extracts from hostP. laevigatashowed the highest antioxidant activity via ABTS•+(2,2′azinobis-(3-ethylbenzothiazdin-6-sulfonic acid) (214.810 ± 0.0802 mg TE/g DW). Fruit extracts with absolute ethanol from theP. laevigatahost showed the highest antihypertensive activity (92 ± 3.054% inhibition of an angiotensin converting enzyme (ACE)). Fruit extracts from both hosts showed a minimum inhibitory concentration (MIC) of 6.25 mg/mL and a minimum bactericidal concentration (MBC) of 12.5 mg/mL againstEscherichia coli,Salmonella choleraesuisandShigella flexneri. Interestingly, a significant host effect was found.P. calyculatusfruits extract could be used therapeutically. However, further confirmation experiments should be carried out.