Giorgio J. Baymon, 25, pleaded guilty in Ramsey County District Court to promotion of prostitution.
As part of his plea, two counts against him were dropped and he agreed to testify against co-defendant Brandon D. Barnes, 24, and any other yet-uncharged co-defendants.
Ramsey County Attorney John Choi said in a statement that he was pleased with the plea agreement. "We need to send a strong message that our children are not for sale," he said.
According to the charges, Baymon and Barnes pimped out the girls via an ad on Backpage.com that featured explicit photos.
The men used guns to threaten the girls, a 17-year-old and a 15-year-old runaway. The charges say that the girls had sex with two men who answered the ad, and with one of the defendants' friends, who gave the men marijuana in exchange.
The girls will be treated as victims and will not be charged with prostitution.
Baymon had been charged with two other counts that were dropped in the plea agreement: sex trafficking in minors and inducing minors for prostitution. He faces 14 years in prison and will be sentenced Nov. 29.