Sinnott is a surname, and may refer to:
- Conor Sinnott (born 1986), a professional footballer
- Declan Sinnott, an Irish-born musician and producer
- Edmund Ware Sinnott (1888–1968), an American botanist and textbook author
- Herbert Arthur Sinnott (1871–?), the 21st mayor of Calgary, Alberta
- Joe Sinnott (born 1926), an American comic book artist
- John Sinnott (1829–1896), an Irish recipient of the Victoria Cross
- Kathy Sinnott (born 1950), a disability rights campaigner and politician representing Ireland
- Lee Sinnott (born 1965), an Irish ex-professional footballer
- Lillian Sinnott (1890–1914), an American actress of the stage
- Nicholas J. Sinnott (1870–1929), a US Representative from the state of Oregon
- Paul Sinnott, an English drummer
- Will Sinnott (1960–1991), a Scottish musician and songwriter
- William Sinnott (1886–1965), an American detective and Congressional Gold Medal recipient