Ginty moved to California in the 1970s, where he found frequent work as a strong-armed player on television action, appearing in different series in the mid-1970s. In 1975, he appeared in the NBC television movie John O'Hara's Gibbsville (also known as The Turning Point of Jim Malloy). In 1976, he attained some popularity after finding a steady role starring with Robert Conrad in Baa Baa Black Sheep, a successful television series about the experiences of United States Marine Corps aviator Pappy Boyington and his squadron of misfits during World War II.

Ginty was born in Brooklyn, New York, the son of Elsie M. (née O'Hara), a government worker, and Michael Joseph Ginty, a construction worker. Ginty was involved with music from an early age, playing drums with Jimi Hendrix, Janis Joplin, Carlos Santana and John Lee Hooker. He studied at Yale and trained at the Neighborhood Playhouse and the Actors Studio. Ginty worked in the regional theater circuit, and New York theatre Broadway. Harold Prince hired him as his assistant after seeing him perform in The New Hampshire Shakespeare Festival Summerstock Company under the direction of Jon Ogden 1973.

Ginty had a small role as a popcorn vendor in Two-Minute Warning (1976), and then appeared in two Hal Ashby movies. The 1976 Bound for Glory biography of folk singer Woody Guthrie, starring David Carradine, and Coming Home (1978) with Bruce Dern (a film which was nominated for eight Oscars).

Around the time he was appearing in the series The Paper Chase (1978), he won his first film action lead in The Exterminator (1980), which became a surprising box-office hit. Four years later, he would reprise the action lead in the sequel Exterminator 2. After starring in Exterminator, Ginty's career took a downturn into B-movies, including:

He began working with Narconon that provides drug rehabilitation, drug education and drug prevention programs in 1979.

He became an independent producer/director, and formed his own production company, where he became the head of the company, Ginty Films, buying shares in the special effect studio Introvision that distributed his vehicles both here and abroad. Most were crudely made on very limited budgets, but he had nevertheless done quite well for himself as a writer/producer/director, especially overseas, with such assembly-line fare as Gold Raiders (1983) which was filmed in Thailand, Cop Target (1990), which was shot in France and Woman of Desire (1993). He did not slow down in the late 1990s, performing producing and directing chores on such shows as China Beach (1988), Xena: Warrior Princess (1995), Nash Bridges (1996), Charmed (1998) and Tracker (2001).

Ginty's acting career faded in the 1990s, although he played some higher-quality roles, such as in Tom Ropelewski's comedy Madhouse. Ginty also performed in another big production, with Mickey Rourke and Don Johnson, in Harley Davidson and the Marlboro Man.

In 1992, a 44 year old Ginty portrayed Dr. Vance Talbot in "Fool For Love" on the season 5 13th episode of In The Heat of the Night with Carroll O'Connor. Ginty played a cheating husband who frames his mistress Sally Nash (played by Actress Arlene Golonka-13 years Ginty's senior).