High thermal runway hazard has been the blocking stone on the way of extended usage of epoxy resin (EP). In such context, the method of preparing fire retardant EP composite with inorganic filler has been adapted, and the shining star of transition metal carbides (MXenes, denoted as MX) has evoked the ardent concern. Nevertheless, the inferior flame retardation efficiency, severe agglomeration, surface scarcity of organic groups have collectively appealed to design MX based flame retardant (FR) with high efficiency. Here, the hydrogen bonding induced strategy and in-situ growth method are utilized to gain FR of P-MX@UIO. Under 2.0 wt% loading, the reductions on peak heat release rate and total heat release reach 48.9% and 45.4%. Meanwhile, the decreases in peak smoke production and total smoke production approach 48.6% and 43.6%. Also, the peak CO production rate is impaired by 48.3%. Such strengths both in suppressing heat and toxicants emissions, are vividly validated via comparison with previous works. Ulteriorly, the inhibited releases of NO and HCN are detected. Peculiarly, the storage modulus is promoted by 75.6% after incorporating P-MX@UIO. This work may inspire the judicious design of MX based FR and fire-safe polymer composites.