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Alpha-amylase (AMY) plays a significant role in regulating the growth, development, and postharvest quality formation in plants. Nevertheless, little is known about the genome-wide features, expression patterns, subcellular localization, and functional regulation of <i>AMY</i> genes (<i>MaAMYs</i>) in the common starchy banana (<i>Musa acuminata</i>). Twelve MaAMY proteins from the banana genome database were clustered into two groups and contained a conserved catalytic domain. These <i>MaAMYs</i> formed collinear pairs with the <i>AMY</i>s of maize and rice. Three tandem gene pairs were found within the <i>MaAMY</i>s and are indicative of putative gene duplication events. <i>Cis</i>-acting elements of the <i>MaAMY</i> promoters were found to be involved in phytohormone, development, and stress responses. Furthermore, <i>MaAMY02</i>, <i>08</i>, <i>09</i>, and <i>11</i> were actively expressed during fruit development and ripening. Specifically, <i>MaAMY11</i> showed the highest expression level at the middle and later stages of banana ripening. Subcellular localization showed that MaAMY02 and 11 were predominately found in the chloroplast, whereas MaAMY08 and 09 were primarily localized in the cytoplasm. Notably, transient attenuation of <i>MaAMY11</i> expression resulted in an obvious increase in the starch content of banana fruit, while a significant decrease in starch content was confirmed through the transient overexpression of <i>MaAMY11</i>. Together, these results reveal new insights into the structure, evolution, and expression patterns of the <i>MaAMY</i> family, affirming the functional role of <i>MaAMY11</i> in the starch degradation of banana fruit.