Rupert Colville, spokesperson for the UN High Commissioner for Human Rights, said the stations remained suspended for a third day on Friday "in spite of an interim order by a Kenyan high court".
"We call on the government to respect and implement the judicial decision," Colville said in a statement.
The government said broadcasting the mock swearing-in ceremony - at which Odinga declared himself the "people's president" - threatened national security.
It also described the event as an attempt to overthrow President Uhuru Kenyatta.
Drawing tens of thousands of Odinga's supporters, the ceremony came three months after the opposition leader boycotted a presidential election rerun.
The country's High Court ordered a 14-day suspension of the government's shutdown on Thursday while a legal challenge could be heard.
Journalists and human rights groups have condemned the media shutdown as an attack on freedom of the press.
"The government allowed the event to take place," Linus Kaikai, managing editor of Kenya's Nation Media Group, told Al Jazeera earlier this week.
"I didn't understand the minister's rationale on why they allowed the event, but cannot allow coverage."
US State Department spokesperson Heather Nauert said the US was "deeply concerned by the government's action to shut down, intimidate, and restrict the media".
"We urge the government and all Kenyans to respect freedom of expression and implement court orders calling for the restoration of television broadcasts," she said.