"Santa Claus is Coming to Town" (sometimes with Coming changed to Comin') is a Christmas song. It was written by John Frederick Coots

J. Fred Coots

John Frederick Coots was an American songwriter. He wrote over 700 songs.He is most famous for the song "Santa Claus Is Coming to Town", a song that became one of the biggest best sellers in American music history....

 and Haven Gillespie

Haven Gillespie

James Lamont "Haven" Gillespie was an American Tin Pan Alley composer and lyricist. He was the writer of "Santa Claus Is Coming to Town" as well as "You Go to My Head", "Honey", "By the Sycamore Tree", "That Lucky Old Sun", "Breezin' Along With The Breeze", "Right or Wrong," "Beautiful Love",...

, and was first sung on Eddie Cantor

Eddie Cantor

Eddie Cantor was an American "illustrated song" performer, comedian, dancer, singer, actor and songwriter...

's radio show in November 1934.
It became an instant hit with orders for 100,000 copies of sheet music the next day and more than 400,000 copies sold by Christmas.
The earliest known recorded version of the song was by banjoist Harry Reser and his band on October 24, 1934 (Decca 264A) featuring Tom Stacks

Tom Stacks

Tom Stacks was the lead singer, drummer, and sound effects man for many of Harry Reser's late 1920s jazz and novelty bands that included "The Six Jumping Jacks" and "Harry Reser's Rounders"...

 on vocal, the version shown in the Variety charts of December 1934.