| Johnston Cornish | |
| State1: | New Jersey |
| District1: | 4th |
| Party: | Democratic |
| Term1: | March 4, 1893 - March 3, 1895 |
| Preceded1: | Samuel Fowler |
| Succeeded1: | Mahlon Pitney |
| Office2: | Member of the New Jersey Senate from Warren County |
| Term Start2: | 1891 |
| Term End2: | 1893 |
| Predecessor2: | Martin Wyckoff |
| Successor2: | Christopher F. Staates |
| Term Start3: | 1900 |
| Term End3: | 1902 |
| Predecessor3: | Isaac Barber |
| Successor3: | Isaac Barber |
| Term Start4: | 1906 |
| Term End4: | 1911 |
| Predecessor4: | Isaac Barber |
| Successor4: | Thomas Barber |
| Office5: | Mayor of Washington, New Jersey |
| Term Start5: | 1884 |
| Term End5: | 1887 |
| Birth Date: | June 13, 1858 |
| Birth Place: | Bethlehem Township, New Jersey, USA |
| Death Date: | June 26, 1920 (aged 62) |
| Death Place: | Washington, New Jersey, USA |
| Profession: | Politician |
Johnston Cornish (June 13, 1858 – June 26, 1920) was an American Democratic Party politician who represented in the U.S. representative for one term from 1893 to 1895.
Born in Bethlehem Township, New Jersey, Cornish attended the common schools. He moved with his parents to Washington, New Jersey, in 1870. He was graduated from the Easton (Pennsylvania) Business College, and engaged in the manufacture of pianos and organs.
Cornish was elected Mayor of Washington, New Jersey, in 1884, and reelected in 1885 and 1886. He declined renomination in 1887 and in 1888. He served as member of the New Jersey Senate from 1891 to 1893, representing Warren County.
Cornish was elected as a Democrat to the Fifty-third Congress, serving in office from March 4, 1893 to March 3, 1895. He was an unsuccessful candidate for reelection in 1894 and lost again in 1896. He accompanied William Jennings Bryan on his whistle stop tour through New Jersey, pausing in Washington on September 23, 1896.[1]
After leaving Congress, Cornish again served as a member of the New Jersey Senate from Warren County from 1900 to 1902 and 1906 to 1911.
He served as president of Cornish Piano in 1910. He served as member of the New Jersey Democratic State Committee. He served as president of the First National Bank, Washington Water, and the Warren County Bankers' Association at the time of his death in Washington, New Jersey on June 26, 1920. He was interred in the Cornish family plot in Washington Cemetery.