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Abstract De novo metalloprotein design involves the construction of proteins guided by specific repeat patterns of polar and apolar residues, which, upon self‐assembly, provide a suitable environment to bind metals and produce artificial metalloenzymes. While a wide range of functionalities have been realized in de novo designed metalloproteins, the functional repertoire of such constructs towards alternative energy‐relevant catalysis is currently limited. Here we show the application of de novo approach to design a functional H₂evolving protein. The design involved the assembly of an amphiphilic peptide featuring cysteines at tandema/dsites of each helix. Intriguingly, upon Ni^IIaddition, the oligomers shift from a major trimeric assembly to a mix of dimers and trimers. The metalloprotein produced H₂photocatalytically with a bell‐shape pH dependence, having a maximum activity at pH 5.5. Transient absorption spectroscopy is used to determine the timescales of electron transfer as a function of pH. Selective outer sphere mutations are made to probe how the local environment tunes activity. A preferential enhancement of activity is observed via steric modulation above the Ni^IIsite, towards the N‐termini, compared to below the Ni^IIsite towards the C‐termini.