She spoke to about 5,000 people who crowded around the dilapidated headquarters of her political party, the first stop for the Nobel Peace Prize laureate after leaving the lakeside residence that had been her prison.
"I believe in human rights and I believe in the rule of law. I will always fight for these things," she said. "I want to work with all democratic forces and I need the support of the people."
Suu kyi earlier slipped into the small compound of her National League for Democracy as people shouted "We love Suu" amid thunderous applause.
Inside, she met with diplomats and was later scheduled to talk with the media, attend the funeral of a close friend and pay a customary visit to the city's sacred Shwedagon pagoda.
"This is an unconditional release. No restrictions are placed on her," her lawyer Nyan Win said.
There was speculation whether she would use her newfound freedom to challenge the ruling military head-on, or be more conciliatory.
In her speech, she did not sound a strident note, speaking about working toward national reconciliation and saying she bore no grudge against those who had held her in detention for more than 15 of the last 21 years.
