It wasn't until 1975 that Vitali met Stanley Kubrick, with whom he would go on to have a professional relationship for the rest of Kubrick's career. Vitali answered a cast call for Barry Lyndon and got the part of Lord Bullingdon, the title character's stepson. Both Kubrick and Vitali bonded during the shoot. Five years later, Kubrick sent Vitali a copy of Stephen King's The Shining and was asked to join the production of Kubrick's next film, to which Vitali eagerly agreed. He is credited in The Shining (1980) as "personal assistant to director".
In 1977 he portrayed Victor Frankenstein in Calvin Floyd's adaptation of Mary Shelley's classic Frankenstein, where he met his would-be-wife Kersti Vitali, who worked as costume designer in the shoot. The Vitalis then worked as costume designers in Birgitta Svensson's Mackan, after which Leon played a bit part in Svensson's next film, Inter Rail (1981). Leon and Kersti would divorce later on.
Vitali teamed once more with Stanley Kubrick for Full Metal Jacket (1987), where he served both as "casting director" and "assistant to director". Twelve years later, Vitali was credited with the same titles in working with Kubrick in what would be his last movie, Eyes Wide Shut (1999), where he also had a small role playing the ominous Red Cloak who confronts Tom Cruise during the infamous orgy scene. Vitali's name can actually be seen in the third column of the newspaper article that Cruise's character reads to learn about the Ex-beauty queen in hotel drugs overdose. Vitali's cameo in print is as a "fashion designer".
Since Kubrick's death, Vitali has overseen the restoration of both picture and sound elements for most of Kubrick's films. In 2004 Vitali was honored with the C.A.S.'s President's Award for this work.
In 1999, Vitali and filmmaker Todd Field, with whom he appeared in Eyes Wide Shut, began discussing the possibility of making films together. In 2001 they did just that. Vitali is credited as "technical consultant" on Field's In the Bedroom (2001), and as "associate producer" on Field's Little Children (2006), where he also made a cameo appearance as "The Oddly Familiar Man". He recently began work as a producer on Field's upcoming, untitled film, scheduled for release in 2009. This marks their third collaboration.