A concealed bridge assembly is provided for supporting adjacent lateral edges of cooktop units that are mounted in a kitchen countertop. The concealed bridge assembly can be used for traditional raised mounting of cooktop units or true-flush mounting of cooktop units. When used with traditional mountings, the concealed bridge assembly has a top that is sized to be flush with the countertop surface and the approximate length of the countertop opening. If true-flush mounting is desired, the top of the concealed bridge assembly is flush with the top surface of a kerf cut in the countertop.