Jumba's lab is a laboratory where Jumba Jookiba created Experiment 626 (later known as Stitch) in Lilo & Stitch before he was arrested by the Galactic Federation for illegal experiment creating. It is also the place where he created 625 more genetic experiments when he worked for Dr. Hämsterviel at the time.
In Leroy & Stitch, after Lilo and Stitch had successfully turned all of Jumba's experiments from bad to good, he was given the confiscated key to his laboratory again. Jumba was at first happy to be returning to many of his "evil genius" ways, but discovered that without anyone to show his accomplishments to, he was as unhappy as Pleakley and his job at GACC.
However, Jumba's sadness was short-lived when Gantu and Hämsterviel barged in. Hämsterviel then forced Jumba to create a new and better experiment to defeat the Galactic Alliance. After Jumba finished creating the experiment and activated it, Hämsterviel named him Leroy. Later, when Stitch burst in to recapture Hämsterviel, the latter ordered Leroy to kill Stitch, and a fight ensued between the two experiments. During their battle, they unintentionally sabotaged Jumba's lab, much to his horror because he had no insurance.