Giuliani, 76, was admitted to MedStar Georgetown University Hospital on Sunday after testing positive for the novel coronavirus. Trump revealed his diagnosis the same day.
"My treatment by the nurses and staff at Georgetown Med Star Hospital was miraculous," Giuliani tweeted Thursday. "I walked in with serious symptoms. I walked out better than ever."
He thanked an "all-star" team of doctors, including White House physician Dr. Sean Conley, as well as Trump, for being a "great president" and "a good friend."
Speaking to ABC Radio on Wednesday, Giuliani said he received some of the same treatments Trump did when he was hospitalized with COVID-19 in October. Trump received supplemental oxygen, the antiviral remdesivir and an experimental antibody treatment called regeneron.
"If it wasn't me, I wouldn't have been put in a hospital, frankly," Giuliani told the radio network. "Sometimes when you're a celebrity they're worried if something happens to you. They're going to examine it more carefully and do everything right."
Giuliani's diagnosis came days after his son, Andrew Giuliani, tested positive for the virus.
In recent weeks, Giuliani had been traveling to various states to represent Trump in his effort to have the presidential election results tossed. State legislatures in Arizona and Michigan announced earlier this week they would shut down work for a week after several members came into contact with Giuliani.