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The B-box zinc-finger transcription factors are important for plant growth, development, and various physiological processes such as photomorphogenesis, light signaling, and flowering, as well as for several biotic and abiotic stress responses. However, there is relatively little information available regarding <i>Brassica</i> B-box genes and their expression. In this study, we identified 51, 52, and 101 non-redundant genes encoding B-box proteins in <i>Brassica rapa</i> (<i>BrBBX</i> genes), <i>B. oleracea</i> (<i>BoBBX</i> genes), and <i>B. napus</i> (<i>BnBBX</i> genes), respectively. A whole-genome identification, characterization, and evolutionary analysis (synteny and orthology) of the B-box gene families in the diploid species <i>B. rapa</i> (A genome) and <i>B. oleracea</i> (C genome) and in the allotetraploid species <i>B. napus</i> (AC genome) revealed segmental duplications were the major contributors to the expansion of the <i>Brassica</i><i>BBX</i> gene families. The <i>Brassica</i><i>BBX</i> genes were classified into five subgroups according to phylogenetic relationships, gene structures, and conserved domains. Light-responsive cis-regulatory elements were detected in many of the <i>BBX</i> gene promoters. Additionally, <i>BrBBX</i> expression profiles in different tissues and in response to various abiotic stresses (heat, cold, salt, and drought) or hormones (abscisic acid, methyl jasmonate, and gibberellic acid) were analyzed by qRT-PCR. The data indicated that many B-box genes (e.g., <i>BrBBX13</i>, <i>BrBBX15</i>, and <i>BrBBX17</i>) may contribute to plant development and growth as well as abiotic stress tolerance. Overall, the identified BBX genes may be useful as functional genetic markers for multiple stress responses and plant developmental processes.