In this work, an in-situ growth of metal coordination-synergistic imprinted polymer onto magnetic FeNi biochar was synthesized and further used for the recognition and isolation of toxic monocrotaline (Mct) from herbal medicines. The shrimp shell-derived iron nickel oxide doped magnetic biochar (INOMB) was successfully prepared by a combined impregnation and pyrolysis method. The molecularly imprinted polymers (MIPs) layer was then in-situ coated onto the surface of the INOMB carrier by the incipient metal coordination interaction between Mct and bimetallic Fe/Ni elements, and dopamine self-autoxidation process. The obtained FeNi@Mct-MIPs was systematically characterized through various characterization techniques. Profiting from the synergistic effect, the synthesized FeNi@Mct-MIPs obviously enhanced the adsorption capacity in capturing Mct, and the maximum adsorption capacity and imprinting factor were determined as 64.59 mg g-1 and 2.16 accordingly. Furthermore, the resultant FeNi@Mct-MIPs composite can be further used as a novel solid-phase extraction absorbent to enrich and detect trace Mct in herbal plants by using ultra-high performance liquid chromatography combined with mass spectrum (UHPLC-MS) technology. Overall, the present INOMB-based composite shows great potential for selective separation and detection of Mct from traditional Chinese medicine samples.