Jenkins' attorney, Lott Brooks III, said his client pleaded guilty to spare his family from having to go through a trial, and that the decision was not part of a deal with prosecutors.
"His feeling was, 'My children are dead. What else could happen to me,"' Brooks said.
Police say Jenkins was driving drunk and using his cell phone on the afternoon of April 18, 2009, when he lost control of his car, which was carrying seven passengers. The vehicle veered off the road and into the ditch, which had been turned into a raging river by heavy rains that day.
Jenkins, his brother and Jenkins' 10-year-old daughter were able to escape. But five children drowned, including three of Jenkins' children -- Devin Jenkins, 4, Hallie Jenkins, 4, and Karrinton Jenkins, 1 -- and brothers Dreton Thompson, 11, and Malik Barlow, 7.
Prosecutor Alison Baimbridge said she was confident in the state's case against Jenkins.
"By pleading guilty, he took responsibility for his actions," said Baimbridge.
But Monday in court, state District Judge Mary Lou Keel questioned the genuineness of Jenkins' guilty plea before accepting it.
Keel asked Jenkins what had caused the car to go out of control and in a low voice he responded he had consumed alcohol, but only a cup of brandy with coke.
"The car went out of control ... it was the rain," Jenkins said.
"You're telling me you're not really guilty," Keel said. "How did you cause this wreck?"
"By being intoxicated," Jenkins responded.
Baimbridge said evidence would have shown that Jenkins had a blood alcohol level of 0.12 percent at the time of the accident and that even 2 1/2 hours after the crash, he was still right at the legal limit of 0.08 percent. Blood tests also revealed that Jenkins had PCP and marijuana in his system, she said.
Brooks said the blood tests were questionable and he would have contested them at trial.
Jenkins' sentencing is in two months. Intoxication manslaughter has a maximum sentence of up to 20 years, but because Jenkins has a previous felony conviction for possession of a prohibited firearm, he could face up to life in prison for each count.