Liquid organic hydrogen carriers (LOHCs) are an effective solution for the long-term storage of hydrogen and its long-distance transportation, but one that requires efficient catalysis for hydrogen uptake and release. Homogeneous molecular catalysts employed in LOHC systems usually exhibit high reactivity and selectivity but are difficult to recover and reuse, a fact that severely limits their practical application. Herein, we report an easily synthesized polymer-grafted pincer-type complex of earth-abundant manganese, which can catalyze the aqueous dehydrogenation of methyl formate, an emerging LOHC material. Importantly, this immobilized Mn-pincer catalyst retains the high reactivity of the corresponding molecular catalyst, yet is also recyclable, exhibiting high stability and achieving a total hydrogen-based turnover number of more than 230000 after 5 consecutive recycling rounds.