The executions were announced Thursday by Indonesia's recently appointed Attorney General HM Prasetyo, who said in a statement that preparations for the executions were almost complete.
He said the executions had been scheduled after petitions for clemency to Indonesian President Joko Widodo were rejected late last month. Widodo had previously told a university audience he planned to reject the 64 appeals for clemency he had received from drug offenders on death row.
The four men and two women to be executed hailed from Brazil, Malawi, Nigeria, the Netherlands, Vietnam and Indonesia, said Prasetyo.
Among them is Brazilian Marco Archer Cardoso Moreira, 53, who would be the first of his countrymen ever to be legally executed abroad, said Leonardo Monteiro, counselor at the Embassy of Brazil in Jakarta.
"The embassy of Brazil is doing its best to try to postpone the execution," he told CNN, saying it was scheduled for this weekend.
"We are trying everything we can through the proper channels."
Brazil does not have the death penalty on its books, he said.
The condemned man had been in jail since 2003, after having been caught at Jakarta airport with 13 kilograms of cocaine, he said.
Sentenced to death in 2004, he lodged a petition for clemency in 2010, according to a statement from the Attorney General's office.
The government of the Netherlands is also protesting the planned execution of Indonesian-born Dutch citizen Ang Kiem Soei, who was condemned to death in 2003 for drug trafficking.
"The Netherlands resolutely condemns the planned execution," Friso Wijnen, spokesman for the Foreign Affairs Ministry of the Netherlands, told CNN, adding that his government was making "every effort to the highest level" to prevent it.
Also sentenced to death and facing likely execution this year are the two Australian ringleaders of the so-called "Bali Nine" ring, arrested in 2005 with more than 8 kg of heroin.
Human rights groups have slammed the executions, calling for them to be stopped.
"Tackling rising crime rates is a legitimate goal of President Widodo's administration, but the death penalty is not the answer and does not work as a deterrent to crime," said Rupert Abbott, Amnesty International's research director for Southeast Asia and the Pacific.
Phelim Kine, deputy director of Human Rights Watch's Asia division, accused Indonesia of double standards in lobbying to prevent the execution of its nationals overseas, but refusing requests by the Brazilian government to extradite Moreira to serve out his sentence in his home country.
Indonesia, which has extremely strict drug laws, carries out executions by firing squad.
The country resumed executions in 2013 after a four year break, but no executions were carried out in 2014.