The traditional monarch, who ascended the throne of Uganda's Tooro Kingdom as an infant in 1995, died last month from cancer. He was 34.
He was buried on Saturday next to his ancestors after an emotional funeral service in an Anglican cathedral in the remote city of Fort Portal, near the Congo border, concluding a nine-day mourning period.
Elders with the kingdom's ruling clan, known as the Babiito, said Oyo, who was unmarried, never declared an heir to them, disputing the account of others in the kingdom who said he left behind a son born out of wedlock.
The son has not been publicly identified, leading to sensational claims on social media of at least two possible heirs alleged to be Oyo's children.
On Wednesday, a committee of Tooro elders announced that they had chosen a prince working as a journalist to succeed Oyo, earning praise from traditionalists who want an adult on the throne and rebuke from Oyo's closest relatives.
Oyo's sister, Ruth Komuntale, said the announcement sought to "bring division and turmoil".
Queen Mother Best Kemigisa said in a statement that the succession battle undermined their ability to mourn the king's death.
"I also appeal to those fighting over the throne: please, there will be time for all of that," she said in a statement.
"Let us grieve and bury my son King Oyo."
Oyo was crowned in 1995, at the age of three, after his father's death.
He was a curious child in colourful robes and an object of adoration for his hundreds of thousands of followers.
At his coronation, he went through a series of tribal rituals and was led into the royal cemetery to perform a coming-of-age ceremony: successfully tossing nine coffee beans into his father's tomb.
The matter of Oyo's successor could still go to the courts, after his family said he left behind a will that had been ignored by Tooro elders.
Oyo once held the unofficial title of the world's youngest king, a mesmerising figure even for world leaders introduced to him at national events, including South Africa's Nelson Mandela.
Oyo was guided by regents appointed by the kingdom until he became an adult at 18.
"This is one of those deaths, the Bob Marley kind, that one never heals from," Timothy Kalyegira, a prominent analyst who is from Tooro, said in a eulogy posted on social platform X.
"Not Oyo; not that likeable young man; not at 34. That's what makes it so painful."
The late Libyan leader Muammar Gaddafi befriended the Tooro royal family as if they were part of his extended family.
He made multiple trips to Uganda and supported Oyo and his mother for years before his death in October 2011.
Uganda's traditional kingdoms were banned after independence from British colonial rule by a republican president who said he wanted to unify the country, but they were restored in 1993.
Although they have no political authority and are legally not allowed to engage in partisan politics, monarchs wield authority as guardians of tribal culture.
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