DeWitt Clinton High School is a public high school located since 1929 in the Bronx borough of New York City. Opened in 1897 in Lower Manhattan as an all-boys school, it maintained that status for 86 years before becoming co-ed in 1983. From its original building on West 13th Street in Manhattan, it moved in 1906 to a new location at 59th Street and Tenth Avenue (Haaren Hall at the John Jay College of Criminal Justice). In 1929, the school moved to its home on Mosholu Parkway in the Bronx, which more recently has been across from the Bronx High School of Science. After more than a century of operation, DeWitt Clinton High School since the early 2000s has dealt with serious problems of student performance, gang culture, and security.

The school originally opened in 1897 at 60 West 13th Street at the northern end of Greenwich Village under the name of Boys High School, but this should not be confused with the Boys High School that was located in Brooklyn. In 1900, the school was renamed in honor of politician DeWitt Clinton, who had served as a United States senator, as the mayor of New York City and then as the sixth governor of New York during the early 19th century.

In 1906, the school moved to a newly constructed building on Tenth Avenue, between 58th Street and 59th Street, in the Hell's Kitchen neighborhood. That year also saw the opening of the nearby DeWitt Clinton Park, where students farmed plots in the first community garden in New York.

The school's H-shaped building, designed by C. B. J. Snyder, was said to be the largest high school building then in the United States. After the school moved to the Bronx in 1929, this building became Haaren High School. It became known as Haaren Hall on the campus of the John Jay College of Criminal Justice.

Until high school education became compulsory in the early 1930s, Clinton – like all other public schools in the city – had a classics department where Ancient Greek and Latin were taught. Perhaps its most famous educator was Dr. Irwin Guernsey, a history teacher known to generations of students as "Doc" Guernsey. He came to Clinton in the fall of 1914 and retired in the spring of 1959, due to illness. Using two "Irish" canes, he taught from his chair and won the title of Master Teacher in New York City twice in his career. He was also head of the Honors Association, Arista. The History wing is named "Guernsey Hall" in his memory, and one can still see the library cart named "Doc's Special" on which he sat while students wheeled him to class during the last years of his tenure, when he was sick.

In 1929, the school moved to a new building on a 21-acre (85,000 m²) campus at 100 West Mosholu Parkway South and East 205th Street in the Bedford Park section of the Bronx, where it has remained. Paul Avenue, which runs to the side of the school from Mosholu Parkway to Lehman College, is named after a DeWitt Clinton High School principal, Dr. Paul. It was under this principal that the school moved to its location in the Bronx.

During the 1930s, its enrollment peaked at 12,000, and it was said to be the largest high school in the world. Enrollment by 1999 was about 4,000. In 2021, the New York City Department of Education reported 1,118 students.

It remained the last gender-segregated public school in New York City until 1983.