Kenneth Lee Osborn was born in Santa Monica, California, in 1964. His family moved to Huntington Beach, in Orange County, in 1966. He graduated from Fountain Valley High School in 1982, and went on to California State University Fullerton, where he received a B.A. in Communications in 1986. In February 1983, while still a student, he joined the U.S. Marine Corps Reserve, where he was trained as a field radio operator and where he remained for two years, attaining the rank of Corporal. After a short tour with the California National Guard, Osborn joined the Army ROTC program at California State University Fullerton, where he held the positions of Junior Cadet Commander, Battalion Supply Officer, and Senior Class Advisor. He also served concurrently as the Public Affairs Officer of the 311th Corps Support Command. Upon his graduation in 1986, Osborn was commissioned a Second Lieutenant in the U.S. Army Reserve and assigned as a platoon leader to the 361st Supply Company. He served in the company about three years, ending his tour as its executive officer. He was then assigned to the staff of the 155th Corps Support Battalion in South El Monte, and by mid-June 1993 was serving as a 1st Lieutenant in the 304th Material Management Center in West Los Angeles.
Osborn was called up for active duty during Desert Storm (1990/1991), and it was while he was stationed at Ft. Lewis that he came to the realization that he was gay. In 1993, he joined with Lt. Col. Jane Able (a pseudonym), Petty Officer Robert J. Heigl, 1st Lieutenant Donita Holloway, SGT Steven Spencer, Lieutenant Richard von Wohld, and Seaman Werner Zehr, in the first pro-active legal challenge to the Clinton Administration's "Don't Ask, Don't Tell" policy regarding gays and lesbians in the military. Originally filed n the 2nd District Court for the District of Columbia (Roe v. Aspin, No. 93-1549) in July 1993, the suit was refiled in the District Court for the Eastern District of New York (Able v. United States, No. 94-0974) on March 7, 1994. While District Court Judge Eugene H. Nickerson twice ruled that the "Don't Ask, Don't Tell" policy was unconstitutional, on both occasions he was overruled by the 2nd Circuit Court. In December 1998, the Circuit Court denied the plaintiffs' petition for a rehearing, thus effectively ending their challenge to the "Don't Ask, Don't Tell" policy. In a twist of irony, while the case was before the courts the plaintiffs had been protected from discharge from the military by a temporary restraining order, and during that time Osborn had been promoted to Captain and had been activated and served a tour in Bosnia.
During the course of his court challenge to "Don't Ask, Don't Tell", Osborn became involved in the gay veterans movement, serving as Vice President of Public Affairs of the Gay, Lesbian & Bisexual Veterans of America (GLBVA) in 1995-1996, as well as President of the organization's Long Beach/Orange County chapter. In 2004, he served as Public Affairs Office and Vice President, Region 5, of American Veterans for Equal Rights.
Osborn currently resides in the Atwater Village district of Los Angeles, where he is a member of the Atwater Village Neighborhood Council.