Career
His credits as a writer include Saturday Night Live, Late Show with David Letterman, Late Night with Conan O'Brien, The Dana Carvey Show and the Chris Rock Show. His work for the Chris Rock Show was nominated for an Emmy Award three times, including winning "Best Writing in a Variety or Comedy Series" in 1999. He was also nominated for an Emmy Award for his work writing Late Night with Conan O'Brien. However, the feature film, Pootie Tang, born from the sketch show received largely negative reviews.
In 2001, C.K. co-wrote the Chris Rock film Down to Earth. In 2007 he co-wrote the movie I Think I Love My Wife with Chris Rock.

Writing
He has performed his stand-up frequently on shows like Late Night with Conan O'Brien, The Tonight Show with Jay Leno, and Jimmy Kimmel Live. In August 2005, C.K. starred in a half-hour HBO special as part of the stand-up series One Night Stand. Most recently his subject matter reflected his frustrations and anxieties from raising his four-year-old daughter. He was ranked #98 on Comedy Central's list of the 100 Greatest Stand-ups of All Time. There was a small controversy about his placement. When '80s prop comic Gallagher was ranked #100 on the list, he was angry and remarked "I don't even know who Louis C.K. is!"
In 2007, C.K. starred in his own hour-long HBO special titled Shameless.

Stand-up
In June 2006, he began starring in Lucky Louie, a sitcom he created with executive producer Mike Royce. The series premiered on HBO. The show was filmed in front of a live studio audience; it was HBO's first series in that format. Lucky Louie is described as a bluntly realistic portrayal of family life. However, HBO cancelled the series after its first season.

Voice acting
Louis is a frequent guest on the Opie and Anthony radio show, which also stars his Lucky Louie co-star Jim Norton, and he will be a part of Opie and Anthony's Traveling Virus Comedy Tour with other comedians in 2007.
Louis frequently works with Robert Smigel on TV Funhouse shorts exclusively to Saturday Night Live, ranging from politics to surrealism.
Currently, C.K. is set to appear in the upcoming films The Better Man and Diminished Capacity.