Johnson serves as a guide to the player-character Chell as she explores an abandoned part of the Aperture Science facility, though all of his messages are pre-recorded from before the events of the Portal games.

[4][5] Johnson was envisioned since Portal as an "industrial, Southern guy" who would contrast with the "anti-septic" and "politically correct" nature of Aperture Science.

Johnson's voice actor, J.K. Simmons, spoke original lines for various trailers for Portal 2, including at the PAX East exposition in 2011.

[8][9] Cave Johnson does not appear directly in Portal 2, but his image is seen in paintings and his voice is heard in pre-recorded messages as protagonist Chell traverses abandoned parts of the Aperture Science facility.

[citation needed] In 2022, Simmons once again reprised his role as Cave Johnson for the Steam Deck tech demo Aperture Desk Job.

The game takes place some years after Cave's body has died, but his personality has been implanted in a giant computer encased in a stone carving of his own head.

[16] Alice Bell of Rock Paper Shotgun praised his portrayal in Aperture Desk Job, stating that in retrospect of all the character's actions, despite being written as "charismatic and funny, and kind of a caricature of a shouty 80s businessman, he's also obviously a gold plated dickhead".

She described it as being "hoist on his on petard, trapped in a hell of his own making that he asked for, is the perfect Greek underworld-style ironical punishment for Cave Johnson.