In 1995, he began his five season run on The WB's "Unhappily Ever After". A somewhat crude family sitcom, in the "Married... With Children" mold, the series featured Berfield as Ross, the youngest and most considerate of the Malloy clan. Often underused in that sitcom, the young character still played an integral part in the series' plot, as the one who gifts his lonely father with Mr. Floppy, the stuffed bunny who becomes the former head of the household's magically animated confidante. As a veteran player on this The WB sitcom, Berfield was no stranger to skewed sitcom families, and he would become a part of one of the most talked about although unnamed ones as a regular on the acclaimed and highly rated sitcom "Malcolm in the Middle" (Fox, 2000- ). Here he played Reese, second eldest of four rambunctious boys with an unmatchable penchant for troublemaking. Less sharp and more brutal than his younger brother Malcolm, Reese was still an active participant in elaborate but ill-fated schemes, and made a good action-based foil for the cerebral titular character.
While Berfield has done most of his work on television, he was featured in a handful of direct-to-video children's films, including the 1998 release "Mom, Can I Keep Her?" (1998), and 1999's sci-fi comedies "The Kid With X-Ray Eyes" and "Invisible Mom 2". Other film work included a role in the independent drama "Wanted", which debuted on Cinemax in lieu of a theatrical release.