Combretum glutinosum and Mitragyna inermis are two plants used in Benin as a dewormer and antibiotic in traditional human and veterinary medicine. This study aimed to evaluate the anthelmintic, antimicrobial and antioxidant activities of the both plants tannin extracts. The extracts were tested in vitro on Haemonchus contortus larvae and worms and on the growth of 11 reference strains by agar medium diffusion method. Their chemical compositions were determined by UPLC-DAD-ESI-MS. It was found that total tannins extracted from plant leaves showed a strong inhibition on H. contortus larvae and adult worms compared to the negative control. Concerning the antimicrobial activity, M. inermis extract had an effect only on Pseudomonas aeruginosa with a MIC of 2.5 mg/mL. C. glutinosum extract inhibited the growth of most microbial strains with MIC values ranging from 1.25 to 20 mg/mL. The DPPH test showed that the extracts of C. glutinosum (IC 50 = 8.04 µg/mL) and M. inermis (IC 50 = 11.21 µg/mL) have good antioxidant activity and these results are confirmed by the FRAP method. Four (4) compounds could be identified in the tannin extract of C. glutinosum and could explain its activities. The results obtained from this work revealed that the tannins extracted from C. glutinosum showed better anthelmintic, antimicrobial and antioxidant activities compared to the extracts from M. inermis.