Schmidt was born in Wichita, Kansas, to Kathy and Kent Schmidt. His brothers, Kenneth and Kevin Schmidt, are actors. His most recent work includes a collaboration with Hilary Duff on the track, "Night Like This" for her fifth studio album, "Breathe In. Breathe Out", released on June 12, 2015 by RCA Records. He began his acting career at age five, appearing in a Chex TV commercial. When he was nine years old, he was one of two young actors who were hired to be Haley Joel Osment's stand-in and body double (they shared the same agent) in the Steven Spielberg film, A.I. Artificial Intelligence. He celebrated his birthday on the set, and Spielberg and the cast surprised him with a birthday cake decorated with Star Wars figures. When he was 10 years old, his family finally made the move from Kansas to California. Schmidt soon landed recurring roles on General Hospital, Titus, Raising Dad, Gilmore Girls and CSI: Miami. He guest-starred on a variety of TV shows, including ER, MADtv, Frasier and Phil of the Future. Most recently, Kendall guest starred on Without a Trace and Ghost Whisperer. On the big screen, he has appeared in Minority Report and According to Spencer. In 2009, Schmidt was cast as the lead of the TV show Big Time Rush. Kendall portrays a character like himself with the name of Kendall Knight, the calm and relaxed member of Big Time Rush. He is the youngest of the Schmidt brothers. Schmidt is the Lead Singer of boy band Big Time Rush. They have released 3 albums so far that have gone platinum/ and multi platinum and Gold as well. Schmidt is also part of a duo called Heffron Drive. The duo consists of Schmidt and Big Time Rush's current guitarist, Dustin Belt.
In 2013, it was announced that Schmidt will be making solo music. He went on tour with his band, Heffron Drive. The tour was called the Heffron Drive Winter Tour. A 2015 tour that will take place around the world is being planned. Heffron Drive released their first single, "Parallel", on March 25, 2014, and their first album, Happy Mistakes, later that same year. The band is currently working on an acoustic version of the album, titled Happy Mistakes Unplugged. In 2015, Schmidt was featured on a Hilary Duff track called "Night Like This" from her new album Breathe In. Breathe Out..