The 1912 U.S. National Championships (now known as the US Open) took place on the outdoor grass courts at the Newport Casino in Newport, United States. The men's singles tournament ran from August 19 until August 26 while the women's singles and doubles championship took place from June 10 to June 15 at the Philadelphia Cricket Club in Chestnut Hill. It was the 32nd staging of the U.S. National Championships, and the second Grand Slam tennis event of the year. The challenge round was abolished in this edition, thus requiring all participants, including the defending champion, to play the main draw.

Finals

Men's singles

🇺🇸 Maurice McLoughlin defeated 🇺🇸 Wallace F. Johnson 3–6, 2–6, 6–2, 6–4, 6–2

Women's singles

🇺🇸 Mary Browne defeated 🇺🇸 Eleonora Sears 6–4, 6–2

Men's doubles

🇺🇸 Maurice McLoughlin / 🇺🇸 Tom Bundy defeated 🇺🇸 Raymond Little / 🇺🇸 Gustave F. Touchard 3–6, 6–2, 6–1, 7–5

Women's doubles

🇺🇸 Mary Browne / 🇺🇸 Dorothy Greene defeated 🇺🇸 Maud Barger-Wallach / 🇺🇸 Mrs. Frederick Schmitz 6–2, 5–7, 6–0

Mixed doubles

🇺🇸 Mary Browne / 🇺🇸 R. Norris Williams defeated 🇺🇸 Eleonora Sears / 🇺🇸 William Clothier 6–4, 2–6, 11–9