Mr Luk died Tuesday morning at his home in the capital Juba, according to the Fourth Vice President Rebecca Nyandeng De Mabior.
A family spokesperson confirmed that Luk had been battling an illness for quite sometime, without providing further details.
Nyandeng, who previously worked with Mr Luk at the Former Detainee Alliance, eulogised him as a brilliant politician the entire county will miss.
“John Luk was very honest, hardworking and a brilliant person who devoted his entire life to fight for South Sudan during the liberation processes until his death. He is a person the whole country will miss,” Nyandeng told The EastAfrican.
“His shoes are so big that nobody can fit in. The great memory and a name I cannot never forget is how, we named him as John Luk of the SPLM,” added Nyandeng referring to the ruling party Sudan People’s Liberation Movement.
Luk participated in the liberation process that led to the independence of South Sudan from Sudan and also helped in the drafting of the country’s Constitution in 2011.
Prior to his appointment as minister of East African Affairs he had served as the Justice minister from July 2011 until March 2020.
He has also previously served minister of transport.