North Korea's leader Kim Jong-Un has spoken of the "elimination of factionalist filth" in his first public reference to the execution of his uncle.
It was announced on 13 December last year that Chang Song-thaek had been killed for acts of treachery.
The move raised fears of instability in the secretive nuclear-armed country, the BBC reports.
In a new year's message, Kim Jong-Un told state television that actions to eliminate factionalist filth within the ruling Workers' Party has bolstered the country's unity.
"Our party's timely, accurate decision to purge the anti-party, anti-revolutionary elements helped greatly cement solidarity within our party," he said, accusing Mr Chang of trying to build his own power base within the ruling party.
Mr Chang was married to the sister of late leader Kim Jong-il and is believed to have mentored Kim Jong-un when he succeeded his father in 2011.
Although seen as the second-most important figure in the country, he was dramatically removed from a special party session by armed guards and stripped of all titles.
State news agency KCNA later said he had admitted at a military trial of trying to overthrow the state and had been executed immediately.
Analysts said one theory for Mr Chang's downfall was that he was too keen an admirer of China's economic reform.