Efforts to generate organomanganese reagents under ball‐milling conditions have led to the serendipitous discovery that manganese metal can mediate the reductive dimerization of arylidene malonates. The newly uncovered process has been optimized and its mechanism explored using CV measurements, radical trapping experiments, EPR spectroscopy, and solution control reactions. This unique reactivity can also be translated to solution whereupon pre‐milling of the manganese is required. A manganese‐mediated reductive dimerization of arylidene malonates by ball milling is reported. The process has been optimised and its mechanism explored by CV measurements, radical trapping, and EPR spectroscopy. Control experiments identify the action of ball milling rather than mortar and pestle is necessary to realise the effective activation of manganese, which can then be used in either solution or a ball mill for subsequent reactions.