Firefighters received a call in the afternoon from the horse's owner, who said she was riding the horse when she was bucked off. She told firefighters the horse ran into heavy brush, which was about shoulder-high.
A helicopter was summoned and crews spotted the white horse stuck in the brush.
Rescue equipment including Heavy Rescue 6 from Irvine and fire trucks from Mission Viejo and Buena Park were sent to the rural location, a fire official said.
Eleven firefighters hiked in to where the horse to clear the brush. Four more were flown in with chainsaws to clear a path.
The horse was walked out fromt he 100-foot-deep ravine and reunited with its owner shortly after 7:30 p.m.