Overmolded microelectronic packages containing knurled base flanges are provided, as are methods for producing the same. In various embodiments, the overmolded microelectronic package includes a molded package body, at least one microelectronic device contained in the molded package body, and a base flange to which the molded package body is bonded. The base flange includes, in turn, a flange frontside contacted by the molded package body, a device attachment region located on the flange frontside and to which the at least one microelectronic is mounted, and a knurled surface region. The knurled surface region includes a first plurality of trenches formed in the base flange and arranged in a first repeating geometric pattern. The molded package body extends or projects into the first plurality of trenches to decrease the likelihood of delamination of the molded package body from the base flange.