Lyle, a singing Crocodile from Bernard Waber’s series of books, was discovered by Hector P. Valenti (Javier Bardem), an aspiring performer, and befriended by Josh Primm (Winslow Fegley). The Primms met Lyle when they moved into the house where Lyle was living in the attic. Lyle likes caviar, baths, and music. The Primm’s neighbor Mr. Grumps (Brett Gelman) and his cat Loretta don’t like Lyle, and it sets off a series of events. Lyle, Lyle, Crocodile is a live-action movie with Shawn Mendes wearing the Crocodile costume and performing the songs. Lyle, Lyle, and Crocodile use computer-generated images.
After being told no, Hector sneaks into an audition with a magic act but is rejected again. So, Hector goes to a pet store to add an animal to his show. He hears a singing Crocodile, takes it home, and names it Lyle. The Crocodile can’t sing at home until Hector hides him in a scarf. Hector and Lyle practice a duet, Hector schedules a gig for them, and Lyle freezes. So, Hector goes on the road leaving a lonely Lyle at home.
After 18 months, the Primms rent Hector’s home. When Josh moves to New York City with his parents (Constance Wu, Scoot McNairy), he must make new friends at a new school. Josh makes friends with Mr. Grump's cat Loretta and takes her to the attic, where he finds Lyle in a glass case. Hector left a note saying the Crocodile is Hector’s best possession.
After a bad day at his new school, Josh hears movement and singing in the attic. Josh and Loretta go to the attic and investigate. He freezes, Loretta attacks, and Lyle accidentally swallows Loretta. Josh chases Lyle out to the street, where Josh is attacked by a homeless man. Lyle roars and scares the man away. Then, Lyle coughs up Loretta. At Josh’s request, Lyle helps Josh get home, and they become friends. Lyle shares his singing ability with Josh. Finding Lyle in the attic of his new home helps Josh adjust.
One night, Mrs. Primm sees Lyle in Josh’s bed and runs out. Josh chases her, tries to explain, and Lyle starts singing. Mrs. Primm accepts the Crocodile, especially after he helps her regain her enthusiasm for cooking. When Mr. Primm notices the change in Mrs. Primm, questions her, and she tells him about Lyle. He is ready to move his family out of the house when Hector arrives. Hector uses their song and dance to win over Lyle again.
In the meantime, Lyle helps Mr. Primm deal with his rowdy students.
Mr. Grumps takes offense to the Primms, calls a neighborhood meeting, and tries to kick them out, but Hector intervenes.
Hector tries to do another show with Lyle, but Lyle freezes again. Animal control arrives, Hector flees, and the Primms try to save Lyle, but Lyle is sent to the zoo. Josh learns that Mr. Grumps bribed Hector to call animal control. So, Hector joins in to free Lyle using his magic tricks.
Josh gets Lyle on a singing show, and Lyle wins over people. The Primms go to court and win. They go on vacation with Lyle singing Crocodile Rock.
Lyle, Lyle Crocodile is now streaming on Netflix.
