The state broke up an unauthorised rally last month but Saturday's event, although closely watched by helmeted riot police, passed off without violence in a sea of flags.
Organisers said 70,000 people joined the demonstration, whereas the official estimate was 4000.
A Rose Revolution in Georgia in 2003, an Orange Revolution in Ukraine last year and a recent uprising in Kyrgyzstan have toppled governments across the former Soviet Union. They were all sparked by elections the opposition said were rigged.
The leader of major Azeri opposition party Musavat, Isa Gambar, told the crowds in Baku, an oil boom town that sits on the Caspian Sea, that the current government had outlived itself and should be dispatched to the "archive of history".
"We deserve democracy and we will get it," said Gambar, who stood unsuccessfully for president in 2003.
One young man brandished a black-and-white photo of US President George Bush bearing the slogan "We want freedom" across it in English.
Greater press freedom
A bright orange banner also called for press freedom, following the murder of an outspoken investigative journalist earlier this year, a parallel with Ukraine where the killing of a reporter helped galvanise the opposition that took power.
But Azeri President Ilham Aliyev, who was elected in October 2003 following the death of his father Haydar in the first dynastic handover of power in the ex-Soviet world, has said there is no chance of a Velvet Revolution in Azerbaijan.
"We deserve democracy and we will get it"
opposition party leader
Aliyev's election triggered bloody opposition-led riots, which were crushed with truncheons, tear gas and dogs and killed at least three people.
Only a handful of opposition deputies sit in Azerbaijan's parliament after a widely condemned 2000 vote and international groups have criticised its human-rights record as well as the rampant corruption that helps keep half its people in poverty.
Mainly Muslim Azerbaijan is emerging as a hub of Caspian Sea oil production and is the start point for a major new pipeline due to pump oil west. Both the West and Russia wish to see stability there.