The film Pinocchio marked Jiminy's debut. He is first seen singing When You Wish Upon A Star next to a book about Pinocchio. After a brief introduction to the viewers, he begins recounting the story of Pinocchio.
In the actual story, Jiminy is first seen in raggedy clothing, traveling through a village late one night. He eventually comes to Geppetto's Workshop, which was the only sign of life. He sneaks inside and warms himself by the fire while admiring Geppetto's work. Jiminy then observes as Geppetto finishes the puppet he has been working on. Jiminy overhears Geppetto's wish for the puppet to be a real boy, but brushes it off as impractical, though lovely. Jiminy later watches in amazement as The Blue Fairy brings Pinocchio to life. After a conversation with the fairy, Jiminy is appointed to be Pinocchio's conscience, as Pinocchio must prove himself worthy of being made a real boy. Jiminy then teaches Pinocchio to whistle so that Pinocchio can call him.
The next day, Jiminy oversleeps and rushes to find Pinocchio, who has been sent off to school. However, Pinocchio is instead encouraged to become an actor by Honest John. Despite Jiminy's counseling to go to school, Pinocchio becomes part of the show of Stromboli. Jiminy becomes angry but starts to second guess himself when Pinocchio becomes popular and decides to leave believing Pinocchio doesn't need him anymore. When Jiminy decides to wish Pinocchio good luck, he discovers that Stromboli has locked Pinocchio in a bird cage. Jiminy attempts to crack the lock to they can escape but fails (evidently because, according to him, the lock is "one of the older models"). The Blue Fairy later comes along and frees them, after teaching Pinocchio a lesson on lying.
Before the pair can reach home, Pinocchio is convinced to travel to Pleasure Island, said to be a land for boys by Honest John again. Jiminy manages to sneak on the stage wagon but ends up separated from Pinocchio. Jiminy eventually finds Pinocchio in a pool hall, where he is smoking and drinking with Lampwick. Jiminy attempts to get Pinocchio to leave but is insulted by Lampwick. Jiminy leaves in a huff and attempts to go home. He discovers that boys who come to Pleasure Island are transformed into donkeys, and runs off to warn Pinocchio.
The two are able to leave by jumping into the sea, but not before Pinocchio grows a tail and donkey ears. Finally, at home, they learn via a message that Geppetto has gone searching for Pinocchio and trapped by Monstro. Despite Jiminy essentially being live bait, he follows Pinocchio into the sea to search for Geppetto. However, he is separated from Pinocchio after Pinocchio is swallowed by Monstro. Jiminy is forced to find shelter in a bottle to avoid being eaten by the seagulls.
After Pinocchio and Geppetto escape, Jiminy is the one who discovers that Pinocchio has died as a result while saving Geppetto from Monstro who tried to catch them resulting in his death when he smashed into the cliff wall. At Geppetto's workshop, he is shown to be mourning. Like everyone else, he is overjoyed when Pinocchio is revived as a real boy. He manages to step away from the party and thanks the Blue Fairy for helping them. As recognition of his own contributions, the Blue Fairy rewards him with a solid gold badge declaring him an official conscience.
- He was voiced by the late Cliff Edwards
- In Avengers:Age of Ultron,he draws an inspiration of J.A.R.V.I.S and Vision.
- He was mentioned in the Descendants Mobile Game when Ben mentioned "Jiminy? Like the cricket?"