腐乳、豆腐乳又因地而异称为乳腐、南乳、霉豆腐、酱豆腐、糟豆腐（若以糟腌渍）、猫乳、豆乳，是一种将豆腐利用霉菌发酵﹑腌制，二次加工的豆制食品，为东亚人的常见佐菜，或用于烹调。中国大陆及东南亚、**都有生产，但各不相同，比如苏州的豆腐乳呈黄白色，口味细腻；北京的腐乳，呈红色，偏甜；目前四川有些种类的腐乳，比较辣。臭豆腐也属于豆腐乳的一种。

李日华《蓬栊夜话》记载：“黟县（今安徽黄山市黟县）人喜于夏秋间醢腐，令变色生毛随拭去之，俟稍干投沸油中灼过，如制馓法漉出，以他物笔烹之，……然余曾一染指，直臭腐耳，未睹其神奇也。”腐乳通常用毛霉菌发酵，包括腐乳毛霉（Mucor sufu）、鲁氏毛霉（Mucor Rouxianus）、总状毛霉（Mucor racemosus），还有根霉菌，如华根霉（Rhizopus chinensis）等，但克东腐乳是由微球菌发酵的，武汉腐乳是用枯草杆菌发酵的。

Fermented tofu also called fermented bean curd, lufu, rufu, sufu, tofu cheese, soy cheese or preserved tofu is a form of processed, preserved tofu used in East Asian cuisine as a condiment made from soybeans. The ingredients typically are soybeans, salt, rice wine and sesame oil or vinegar. In mainland China the product is often freshly distributed. In overseas Chinese communities and Southeast Asia commercially packaged versions are often sold in jars containing blocks 2- to 4-cm square by 1 to 2 cm thick soaked in brine with select flavorings.