Happenstance, a portmanteau of happening and circumstance, may refer to:

• Happenstance (film), a 2000 French film by Laurent Firode
• "Happenstance" (CSI), a season seven episode of the American crime drama CSI

• Happenstance (Fozzy album), a 2002 album
• Happenstance (Rachael Yamagata album), a 2004 album
• "Happenstance", a song by The dB's from their 1982 album Repercussion
• "Happenstance", a song by Miles Kane from the album Colour of the Trap

• Happenstance, a novel by Canadian author Carol Shields