"Please rest assured. I am strong and steady! I am walking the halls... talking a lot, eating well and, soon, ready to return home and continue working and taking care of every Brazilian family," he wrote on X and other social media.
The video included in the post showed him walking a hospital corridor with his neurosurgeon, Marcos Stavale.
They were the first public images of Lula, 79, since Monday, when doctors detected intracranial bleeding related to a bad fall he had in October and rushed him to the Hospital Sirio-Libanes in Sao Paulo.
He underwent the surgery on Tuesday to relieve the pressure on his brain, with doctors conducting a trepanation -- drilling through his skull.
Lula's medical team says he suffered no brain damage from the emergency and was doing well post-surgery.
In the posted video, Lula is seen walking and stopping to talk with Stavale and with his wife, First Lady Rosangela da Silva.
The president, wearing blue casual wear, sports a bandage on top of his head where the surgery occurred.
In the accompanying message, Lula thanked the public for the prayers and words from well-wishers, passed on by his wife, and said he looked forward to "many meetings in Brazil and around the world" in the coming year.
"Thank you for your affection and for all the dedication of the medical team. The love I receive keeps me always ready to move on!" he wrote.
On Friday he was taken out of intensive care, and he was expected to be allowed to leave hospital early next week.
The hospital said in a public medical update that Lula remains "under semi-intensive care," which a presidency official explained meant monitoring at regular intervals, instead of around-the-clock, as in intensive care.
Remote working
Despite the doctors restricting visits to family members and saying the president needed to rest, Lula has been sporadically carrying out some of his duties while convalescing.
He has been speaking with officials and signing documents electronically, ministers said.
Lula's vice president, Geraldo Alckmin, has been taking on some of the president's workload but the presidency has not officially tapped him to assume full presidential duties.
The latest medical emergency adds to a list of health problems Lula has suffered over the years, including treatment in 2011 for throat cancer, and a hip replacement operation last year.
On Thursday, doctors performed a follow-up procedure to the surgery by inserting a catheter to block blood flow going through an artery to the area of his head that was operated on, to minimize the risk of a hemorrhage reoccurring.
They also removed a medical drain that had been put in on Tuesday to remove blood from the problem area.
Lula's doctor, Roberto Kalil, has said there were no signs of any complications, and that the longer that persisted, the better for Lula's prognosis.
"Every week, every month plays in favor of a patient who has had a brain hemorrhage," he told a news conference on Thursday.
The Brazilian president's medical emergency this week started when he complained Monday of a headache while in Brasilia.
An MRI scan found a hemorrhage between his brain and the dura mater membrane that protects it, prompting his swift transport to the Hospital Sirio-Libanes -- the country's top medical facility -- for the surgery.
After suffering his fall on October 19, Lula told an official from his Workers' Party that the accident had been "serious."
In the weeks following, the president skipped planned overseas trips. But from mid-November he resumed his active schedule, hosting a G20 summit in Rio and attending a Mercosur summit last week in Uruguay.
Left-wing Lula took up his current mandate in January 2023 after beating the previous, far-right president, Jair Bolsonaro, in a tightly fought 2022 election.
