Mykola Protasov was handed a 13-year sentence on March 15, while Valeriy Kostenko and Oleksandr Popovich each received 12-year sentences.
Gongadze, who published articles about official corruption in his online newspaper "Ukrayinska pravda," was a critic of former Ukrainian President Leonid Kuchma.
He disappeared in September 2000 and his headless body was found in a forest outside Kyiv two months later.
Oleksiy Pukach, the former head of the Interior Ministry's surveillance department, where the three officers worked, is also wanted in connection with the killing. He is being sought on an international warrant.
After years of investigation, police have not tracked down those who ordered Gongodze's killing.
with material from news agencies