Knock three times can refer to:

• "Knock Three Times", a 1970 song by Tony Orlando and Dawn

• Knock Three Times (album), a 1971 album by Billy "Crash" Craddock

• Knock Three Times, a 1917 novel by Marion St. John Webb

• Knock Three Times, a 1968 British television serial that featured Hattie Jacques

• A tap code or secret knock

See also

• Knock Knock Knock, a 2002 EP by Hot Hot Heat