In the early 1990s, John began performing the puppetry for Sweetums, as Richard Hunt was physically unable to. Richard continued performing the dialogue for Sweetums until his passing in 1992, after which Henson took over the character completely.
Henson was the primary performer of Sweetums for almost two decades. In 1987, Jim spoke of his son's performance work as Sweetums in a Washington Post interview. John also performed the part in Muppet*Vision 3D, with dialogue looped by Hunt. In later appearances, such as Muppet Treasure Island, John supplied both puppetry and dialogue. In addition to television and film projects, John made live appearances as Sweetums for a number of events, including a 1992 musical tribute to Jim Henson at the Lincoln Center in Armonk, New York; during the MuppetFest weekend in 2001 and the unveiling ceremony for Kermit the Frog's star on The Hollywood Walk of Fame in 2002.
In the early 1980s, John Henson, with John Kahn, built The Great Hot Air Balloon Circus to decorate the spiral staircase of the townhouse where the company made its home at the time. Although it has been moved to a different location, another of his sculptures now welcomes visitors to the current New York offices. Made of brass and other metallic moving parts, the piece was based on one of his father's own sketches.