Marius Borg Hoiby, 29, who joined the royal family when his mother Mette-Marit married Haakon in 2001, pleaded not guilty to the most severe accusations against him, including those of rape, while admitting to some lesser charges.
If found guilty on all counts by the Oslo district court, he could be sentenced to seven years and seven months in prison, as requested by the prosecution, though the court can increase or decrease the length of the sentence sought.
The seven-week trial has gripped the country, detailing Hoiby's drug addiction, self-made videos of sexual encounters and more than 800 electronic messages entered into evidence. One alleged rape took place in the basement of the crown prince's family home, the court heard.
Interest in the case was boosted by the contrast between the picture-perfect royal family and Hoiby's alleged actions as heard in court, said Ketil Raknes, an associate professor in political communication at the Kristiania University of Applied Sciences.
The case, alongside other crises, has contributed to a decline in the popularity of the royal family.
It has also coincided with Crown Princess Mette-Marit's apology for "poor judgment" in maintaining contact with the late US sex offender Jeffrey Epstein after he was convicted in 2008.
The 52-year-old is the wife of Crown Prince Haakon, the heir to the Norwegian throne.
A Norstat survey out on February 21 - during the trial - showed a fall in the number of Norwegians favouring keeping the monarchy to a record low of 60 per cent, from 70 per cent in January, and a rise to 27 per cent from 19 per cent in those wanting a different system of governance.
In May, the royal family recovered somewhat in popularity, with 64 per cent polled by Norstat supporting the monarchy and 23 per cent wanting a different system of governance.
"It was ... a perfect crisis for the royal family because they had two crises at the same time. And they had a lot of (criticism) for the way they handled the Epstein files," Raknes said.
The verdict will be delivered amid difficult personal circumstances for Mette-Marit, Hoiby's mother, who this month was placed on the national lung transplant list as her health has severely deteriorated.
She suffers from pulmonary fibrosis, a condition that makes it increasingly difficult to breathe. Without a transplant, she has around a year left to live, her doctors have said.
That is somewhat changing people's perceptions ahead of the verdict, Raknes said.
"The coverage is much more sober," he said.
"People are seeing: 'Okay, this is a family who's really struggling and this is not the time for ... playing ... the moral card as high as we maybe have done earlier in this case'."
