By Agence France-Presse
"I have a habit of turning bad anniversaries into good anniversaries by doing beautiful things that outshine bad events," he tweeted.
Dotcom has been battling extradition to the United States since police raided his mansion near Auckland six years ago on January 20.
The FBI alleges Dotcom's Megaupload file-sharing service netted more than US$175 million in criminal proceeds and cost copyright owners more than US$500 million by offering pirated content.
The German-born New Zealand resident has denied any wrongdoing and accused US authorities of pursuing a vendetta against him on behalf of politically influential Hollywood studios.
"Today, 6 years ago, the NZ Govt enabled the unlawful destruction of Megaupload and seizure of my global assets," he tweeted.
"I was arrested for the alleged online piracy of my users. Not even a crime in NZ. My lawyers have served a multi-billion dollar damages claim against the Govt today."
His website was an early example of cloud computing, allowing users to upload large files onto a server so others could easily download them.
At its height in 2011, Megaupload claimed to have 50 million daily users and that it accounted for four percent of global internet traffic.
Dotcom, who turns 44 on Sunday, said by getting married on the anniversary of the raid, he was turning January 20 into a "day of joy".
He separated from his first wife Mona three years ago and announced last year he would be marrying Elizabeth Donnelly, 21 years his junior.
"Getting married and getting justice. What a wonderful day," he tweeted on Saturday.