Anthony Waiters, 31, was the only one of four defendants to go to trial on charges that they held Kyle Ramirez captive inside a Tracy home for a year while he was beaten, burned and shackled to furniture.
The 16-year-old managed to escape to a nearby fitness center in 2008.
Waiters was convicted in November of torture, kidnapping, child abuse and false imprisonment. He'll be eligible for parole after nearly 19 years.
The other three people, including Kyle's legal guardian and the home's owners, reached a plea deal and are each serving more than 30 years.
The Associated Press contributed to this report.