A procession made up mainly of women and children, with some elderly people, left Moria camp walking towards the port of Mytilene, with demonstrators shouting slogans.
They carried a stretcher covered by a shroud to represent the woman killed in Sunday's fire at the camp, which sparked riots the same evening. Another 19 people were injured in the blaze, said Greek police spokesman Theodoros Chronopoulos.
The protesters were calling to be moved off the island immediately and for better living conditions, said Chronopoulos.
At the same time, a delegation from Oxfam France visited the makeshift camp that has sprung up outside the Moria camp, where tents and improvised shelters have spilled over into the olive groves.
"It's worse than I imagined," Cecile Duflot, the head of Oxfam France, told AFP as she waited to enter the camp.
"We are in Greece, a European Union country. More than 40 percent of those living here are children. We need to ensure that the situation changes."
People needed to wake up to the burden that Greece and its islands were carrying, she said, adding: "We cannot be satisfied with what are de facto detention camps."
Moria, Europe's largest migrant camp, was designed for 3,000 people but currently houses 13,000 after a surge of arrivals in recent weeks from Turkey.
Greece announced on Monday it wanted to send back 10,000 migrants to Turkey by the end of 2020 after an emergency cabinet meeting following the fire at the camp.
These returns are provided for in a 2016 agreement between Turkey and the European Union.
The conservative government of Prime Minister Kyriakos Mitsotakis has already announced more naval patrols in the Aegean, closed centres for migrants refused asylum, and plans to overhaul the asylum system.
Greece hosts some 70,000 mostly Syrian refugees and migrants who have fled since 2015, crossing over from neighbouring Turkey.
There are more than 26,000 people in the five migrant camps scattered across the Aegean islands, which have a capacity to welcome only 6,300 or so, according to the latest government figures.