Van der Sloot, who was visibly upset after the decision was issued, admitted this week to killing Stephany Flores in his Lima hotel room. The judges said they took his confession into account, but they still gave him a sentence two years short of the 30-year maximum.
The defendant, 24, stood for much of the more than two-hour session and perspired through his green t-shirt. He drank three cups of water and frequently wiped his face.
The judges ordered van der Sloot expelled from Peru at the end of his sentence and ordered him to pay 200,000 Peruvian new soles, or about $74,500, in reparations to Flores' closest relatives.
Van der Sloot confessed to robbery in addition to murder, admitting that he stole Flores' belongings, including 850 soles (more than $300), credit cards, and the victim's van as a means to leave the country. He fled to Chile and was arrested a few days later.
It was an apparent attempt to win a more lenient sentence, using a plea called an "anticipated conclusion of the process" under Peruvian law. Five days earlier, the three judges delayed the start of van der Sloot's trial after he declined to give a plea after expressing reservations about the "aggravating factors" tied to admitting his guilt.
Van der Sloot's attorney, Jose Luis Jimenez, pressed earlier this week for a shorter sentence.
Jimenez claimed that his client was under special stress the day the 2010 murder occurred, which marked five years after Alabama teenager Natalee Holloway went missing in Aruba.
Van der Sloot -- who, with two others, was among the last people seen with Holloway - was detained twice, but never charged, in the high-profile international case.
"He was pointed at and persecuted. The world had been against him for five years before this case, for a murder he said he never committed and for which there is no evidence whatsoever," said Jimenez.
Investigators have said they believe van der Sloot killed Flores after she found something related to the Holloway case on his computer while visiting him in his hotel room. The two met while van der Sloot was in town for a poker tournament.
Judges on Friday recounted the crime in detail. They described how Flores hit van der Sloot in the face after reading the item on Holloway, leading him to hit her in the face with his elbow. Flores fainted and van der Sloot tried to strangle her, but she was still breathing and so he suffocated her with his shirt.
Van der Sloot then tried to clean the room by removing the sheets and changing his bloodied shirt, they said.
He was ultimately caught while traveling alone in a taxi near the Chilean central coastal city of Vina del Mar.
Holloway's body has never been found, and no one has been charged in relation to the case in Aruba. But van der Sloot does face possible extradition to the United States in a related matter.
In June 2010, a federal grand jury in Alabama indicted him on charges of wire fraud and extortion after allegations surfaced that he tried to extort $250,000 from Holloway's mother, Beth. Van der Sloot offered to provide what turned out to be bogus information about the whereabouts of Holloway's remains in exchange for the money, according to the indictment.
He was allegedly given a total of $25,000, and authorities believe he used that money to travel to Peru for the poker tournament.
Thursday, about six and a half years after Holloway went missing, Alabama Probate Judge Alan King signed an order declaring the teenager legally dead.