Some credit a Franciscan friar traveling with the Gaspar de Portolá Expedition in 1769 with the story that a blunderbuss was lost in the canyon, after which the area was named.

"[4] John (Don Juan) Forster received a Mexican land grant in 1846 and established Rancho Trabuco.

Mining remains from this activity include: tunnels into the sides of the canyon (closed for public safety); the stone foundation of an ore-processing stamp mill; and several dams on the creek.

[13][14] The Vedanta Society of Southern California has the Ramakrishna Mission monastery on 40 acres (160,000 m2) in the canyon, founded in 1942 by author and philosopher Gerald Heard.

Cook's Corner: 3 killed, 6 hospitalized in shooting at historic biker bar in Trabuco Canyon https://www.cbsnews.com/losangeles/news/cooks-corner-at-least-3-killed-6-hospitalized-in-shooting-at-historic-biker-bar-in-trabuco-canyon/