Party delegates to the conference arrived in Pyongyang, the capital, on Sunday, where they were met by flags and placards announcing the meeting.
"Warm congratulations to the representatives meeting of the Workers'Party of Korea!" read one poster.
North Korea's state news agency carried a brief dispatch on Sunday about the arrival of delegates, though provided no details about the meeting itself.
The widely anticipated meeting will be the party's first major gathering since a landmark congress in 1980 where then 38-year-old Kim Jong-il made his political debut. That appearance confirmed he was in line to succeed his father, Kim il Sung, the North Korea founder.
Kim Jong-il came to power when his father died of heart failure in 1994, setting in motion the communist world's first hereditary transfer of power.
Kim is believed to be preparing his third and youngest son, Kim Jong Un, for a similar father-to-son power transition, that has triggered speculation the son could be given a key post at the Workers' Party conference as part of a third-generation power transfer.
Kim Jong Un has been elected to attend Tuesday's party conference as a delegate of the Korean People's Army, South Korea's Chosun Ilbo newspaper reported on Monday, citing a source in North Korea it did not identify.
After Kim Jong Un was elected as a delegate, the party central committee put out internal propaganda proclaiming him to be Kim Jong-il's sole successor, the report said, citing the unnamed North Korean.
Backing by the military is considered a prerequisite for the succession to be carried out smoothly in a country that operates on a "military first" policy and where priority is given to the armed forces.
Kim Jong-il was officially chosen as successor in 1972, when he was elected to the party's central committee, and the same scenario could hold true for Kim Jong Un on Tuesday, reported the paper.
The question of who will take over from Kim Jong-il, believed to suffer from a host of ailments, is important to regional security because of North Korea's active nuclear and missile programmes, and regular threats it makes against rival South Korea.
Some experts fear political instability or even a power struggle if Kim were to die or become incapacitated without clearly naming a successor.