Humphreys played numerous small guest roles in television shows throughout the 1980s up to the present including the role of Dr. Pomerantz on the Sci-Fi show The X Files, as well as roles on The Twilight Zone (the 1985 and 2002 revivals), Smallville, Outer Limits and Da Vinci's Inquest. In 2010, he appeared in Diary of a Wimpy Kid as Robert Jefferson. He appeared with the same role in Diary of a Wimpy Kid: Rodrick Rules (2011), Diary of a Wimpy Kid: Dog Days (2012) and Diary of a Wimpy Kid: Class Clown (2012).