Jordan Kemlo, then 17, targeted the boys, all under 15, while he was there in 2014.
He was extradited from his home in Peterhead, Aberdeenshire, last year. Kemlo admitted a number of sex offences when he appeared at a court in in Tucson, Arizona and will be sentenced next month.
Kemlo, now 22 – who has a similar previous conviction in the UK – was visiting family when he targeted the youngsters, who were all under the age of 15, via Minecraft.
He has now admitted five felony charges, including attempted sexual conduct and molestation of a minor, during an appearance at Pima County Superior Court in Tucson, Arizona.
The offences were committed when Kemlo was 17. He was in the country between February and May 2014.
In reports submitted to the US court system, police state the alarm was first raised when the mother of the victim called officers.
She said that when he returned home to the north-east, her son began “acting out” but was reluctant to talk about what had happened.
He later told his mum that he was attacked by Kemlo while they were playing Minecraft, a video game which has a large fan base of children.
Kemlo is alleged to have spoken to three other neighbourhood children about sexual activity during the same period.
He was flown with US marshals to Arizona in February last year.
At Pima County Superior Court this week, Kemlo pleaded guilty to charges of continuous sexual abuse of a child, attempted sexual conduct with a minor, attempted molestation of a child, solicitation to commit sexual conduct with a minor and attempted molestation of a child.
The Arizona Daily Star newspaper reports his offences could result in a sentence of 18 to 46 years, with a presumptive sentence of 32-and-a-half years.
Kemlo is due to appear for sentencing on 22 April.