Lampy's primary purpose is comic relief in that he display's Alvin's insanity. This is because Alvin is not aware that Lampy is inanimate, despite the fact that he realizes that Lampy never does or says anything. Alvin frequently has one-sided conversations with Lampy and even attempts to do the Villainous Dance of Villainy with Lampy as a partner. He also serves as Alvin's personal night light, which helps him cope with his fear of the dark.
Lampy also reveals Alvin's involvement with the Angry Eyebrows when Alvin is spying on Larry and Lampy does not follow him to his hiding spot. He has a more involved role in The Good, The Bad, and the Eggly, where Alvin plugs him in and places him near the end of a telescope to produce a "Lampy Laser", which Alvin and Greta von Gruesome use to break into the vault at the Bumblyburg Science Lab.