The Miró sale at Christie's auction house in London is aiming to raise €50,000 ($56,600) for the Red Cross humanitarian organisation.
The Barcelona painter's grandson told AFP that he would donate the proceeds of the sale because that is what Miró would have wanted.
"I consider myself as the torch-bearer for his wishes and try to do what he would do if he was still alive," Joan Punyet Miró said.
"Miró was a man who endured many hardships throughout his life. He went hungry, and lived in exile through the Spanish Civil War."
He was also conscious of the Spanish refugees living in camps across the border in southern France during the 1936-1939 conflict, and of the 2,000-odd of their number who sailed from France to Chile on board the SS Winnipeg.
Miró, who had Republican sympathies in the civil war divide, was in France when the conflict broke out, and decided to stay in Paris.
His wife and daughter joined him and lived in France until 1940, when the invasion of Nazi Germany saw him flee back to Spain.
The Catalan artist with his grandson. Family photo: Christie's.
"He always wanted to help the most disadvantaged, the refugees and those in exile, and would be aware that what is happening today in Syria could happen tomorrow in Spain," said Punyet.
Since the Syria conflict erupted in 2011, more than 4.8 million refugees have fled the country.
Miró, who died in 1983 aged 90, had personal reasons to be grateful for the work of the Red Cross.
A doctor from the international organisation saved the leg of his only child, Punyet's then 34-year-old mother, after a nasty car accident in 1965.
She recovered after spending a year in bed.
"My grandfather made a tapestry for the Red Cross in gratitude, because they had saved his daughter, his only child," said Punyet.
Barcelona's Mayoral Galeria d'Art, which is working on the fundraising effort, has exhibited the works in several art spaces.
By Alfons Luna / AFP