Nicholas John Sinnott (December 6, 1870 – July 20, 1929) was an American lawyer and politician who served as a United States representative from Oregon from 1913 to 1928.

[1] He received an Artium Baccalaureus degree in 1892 from the University of Notre Dame and read law with Alfred S. Bennett in 1895.

[3] He served as a Republican member of the Oregon State Senate from Wasco County from 1909 to 1913, being elected in 1909 and 1911.

[1] While in the House he worked to create and enlarge water reclamation projects in Eastern Oregon.

[3] His service terminated on July 20, 1929, due to his death in Washington, D.C.[3] He was interred in St. Peters Cemetery in The Dalles.