Kenneth Glenn Hinson, 48, wiped his eyes and mouth and appeared to cry after the jury read its verdict, which followed about four hours of deliberations over two days.
"I think the verdict says it all," he said as he was escorted from the courtroom.
Authorities had charged that Hinson snatched the 17-year-old girls from their bedroom last year and dragged them one at a time to the underground room hidden beneath a tool shed, where he raped and bound them with duct tape. Prosecutors said Hinson expected the girls to die because the room had no air supply.
However, Hinson testified during the six-day trial that the girls had consensual sex with him. He said they made up the story so they would be able to take drugs from the underground room, which he used to store marijuana.
The two young women were not in the courtroom when Hinson was acquitted. Their mothers and other relatives wept. They declined to comment after the verdict.
If convicted, Hinson had faced a mandatory life sentence without parole under the state's two-strikes law because he was convicted of raping a 12-year-old girl in 1991.
The underground room was about the length and width of a midsized car with a ceiling about 4½ feet high. Hinson testified Sunday that he had built the room behind his trailer where he lived.
Defense attorney Rick Hoefer spent much of his nearly two-hour closing argument Sunday picking apart what he called inconsistencies in the teens' testimony, including how long it took them to call 911 after their alleged escape and whether they saw Hinson with a gun.
Prosecutors said any discrepancies in their stories might have been a result of the trauma the teens went through.
"We are shocked and stunned. We believed Mr. Hinson was guilty as charged. We still believe he is guilty as charged," said Attorney General Henry McMaster, who helped prosecute the case.
Hinson remained in custody on a federal firearms charge because he allegedly had a gun when he was arrested. Convicted felons are not permitted to carry weapons.