The unrest in February 2016 saw police fire warning shots in the air in the commercial district of Mong Kok as they clashed with protesters who hurled bricks torn up from pavements and set rubbish alight.
It was the worst violence the city had seen for decades.
The demonstrations were led by "localist" activists seeking more autonomy from Beijing, as fears grow that Hong Kong's freedoms and identity are under threat from Chinese authorities and the city's pro-China local government.
The violent protests contrasted with the largely peaceful pro-democracy Umbrella Movement rallies of late 2014, which brought some busy streets to a standstill for more than two months.
Law Ho-yin and Lin Yun-faat, both in their 20s, were given three-year sentences Monday after being found guilty last month.
Chris Yung, 19, was sent to a correctional training centre for up to three years.
They had all denied the charges.
"Rioting is a very serious offence," said judge Frankie Yiu. "Sentencing should be severe and serve as a deterrent."
The court heard that Yung and Law were masked and often at the frontline of the clashes. Lin had hurled bricks and was subdued by police, Yiu said in sentencing.
The 2016 violence was triggered by official attempts to remove illegal hawkers from the busy commercial neighbourhood during Lunar New Year celebrations.
The battles were dubbed the "fishball revolution" after a favourite Hong Kong street snack sold by the hawkers, and reflected underlying tensions over the erosion of the city's traditions.
None of the three jailed Monday are well-known campaigners.
The alleged riot ringleaders from localist campaign group Hong Kong Indigenous face trial next year.
Another fishball protester was jailed for more than four years in April for rioting and arson after he set fire to a car.
Three more participants received three-year sentences in March on riot charges.
Rioting carries a maximum 10-year sentence.
A number of activists from the 2014 demonstrations are also currently going through the courts.
The failure of the Umbrella Movement to win reform has led to calls among some young campaigners for complete independence for Hong Kong, infuriating Beijing.
Chinese President Xi Jinping warned that any challenge to Beijing's control over semi-autonomous Hong Kong crossed a "red line" as he visited the city to mark the 20th anniversary of the city's handover by Britain.
In Xi's anniversary speech on July 1, he warned any threat to China's sovereignty and security or to the power of the central government was "absolutely impermissible".
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