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To promote the bioconversion of marine chitin waste into value-added products, we expressed a novel pH-stable <i>Micromonospora aurantiaca</i>-derived chitinase, <i>Ma</i>Chi1, in <i>Escherichia coli</i> and subsequently purified, characterized, and evaluated it for its chitin-converting capacity. Our results indicated that <i>Ma</i>Chi1 is of the glycoside hydrolase (GH) family 18 with a molecular weight of approximately 57 kDa, consisting of a GH18 catalytic domain and a cellulose-binding domain. We recorded its optimal activity at pH 5.0 and 55 °C. It exhibited excellent stability in a wide pH range of 3.0–10.0. Mg²⁺ (5 mM), and dithiothreitol (10 mM) significantly promoted <i>Ma</i>Chi1 activity. <i>Ma</i>Chi1 exhibited broad substrate specificity and hydrolyzed chitin, chitosan, cellulose, soluble starch, and <i>N</i>-acetyl chitooligosaccharides with polymerization degrees ranging from three to six. Moreover, <i>Ma</i>Chi1 exhibited an endo-type cleavage pattern, and it could efficiently convert colloidal chitin into <i>N</i>-acetyl-D-glucosamine (GlcNAc) and (GlcNAc)₂ with yields of 227.2 and 505.9 mg/g chitin, respectively. Its high chitin-degrading capacity and exceptional pH tolerance makes it a promising tool with potential applications in chitin waste treatment and bioactive oligosaccharide production.