Known for his work ethic and his "nice" demeanor, Leno started his career as a stand-up comic performing in nightclubs, bars and any place that would give him even five minutes of stage time. Though he had made the occasional foray onto television in the form of guest appearances on The Tonight Show, then hosted by Johnny Carson, stardom eluded him and he continued to work wherever he was allowed. It has been reported that Leno would sometimes work as many as eight or nine clubs in one evening. He began making more frequent appearances on television when many of his friends and contemporaries became more influential on late night programs. Leno made a record number of appearances on Late Night with David Letterman. His popularity was noted by NBC executives, who decided to make Leno the permanent guest host for The Tonight Show when Joan Rivers left that position.
When Carson retired in 1992 Jay Leno became the new permanent host of The Tonight Show after a long period of debate and negotiation between the network, Leno, and David Letterman. Carson, who wanted the show to go to Letterman, suggested that his friend leave the network. Letterman soon signed a deal with CBS.
Leno provides the voice for the character Crimson Chin on the television cartoon show The Fairly Oddparents.
In automobile collecting circles Jay Leno is known as an avid collector and restorer of cars and motorcycles. He has a very large antique car collection on which he is constanly working in his spare time. He is also a promoter of the mechanical crafts, by his columns in Popular Mechanics and his educational activities.