He told Comic Book Resources that 'Booster' will focus on the early days of the character, who was originally created in 1986 by comic writer Dan Jurgens.
He explained: "It's very Booster 1.0, meaning that he's in the early stages of his career as a hero and [he] is pretty self-serving."
Johns also revealed that Jaime Reyes, the third and current Blue Beetle, will be the version that appears in the episode.
"I always liked the chemistry between him and Booster, so when I was going to do this episode, I wanted to do those two together," he admitted. "I think the story that we came up [with] works really well."
He added that the instalment will include "Beetle's origin, Booster first meeting Clark and Lois and maybe a cameo by someone from Kord industries."
Smallville returns to The CW on January 28.