The leaders of Uruguay and Bolivia are also expected to attend the rally set to replace Chavez’s inauguration for his third term in office.
Earlier, the Venezuelan Supreme Court ordered the ceremony to be postponed until Chavez returns from Cuba where he is receiving cancer treatment.
Venezuelan opposition leader Henrique Capriles has recognized the decision ruled by the country’s Supreme Court to postpone President Hugo Chavez’s inauguration.
Mr. Chavez has been staying in Cuba recovering from his fourth cancer surgery.
Meanwhile, Vice-President Nicolas Maduro is acting as head of state.
Many analysts view Mr. Capriles' statement an important step to settle political instability in Venezuela.
The opposition has earlier insisted that new presidential elections should be held within a month.
Venezuelan authorities called for a massive show of support of cancer-stricken Venezuelan President Hugo Chavez on Thursday, the day he was to be sworn in for another six-year presidential term.
Venezuela's Supreme Court on Wednesday ruled to postpone President Hugo Chavez's inauguration until after he completes a course of treatment for cancer. Chief judge of Venezuela’s Supreme Court, Luisa Morales, said that inauguration of Chavez was unnecessary as he served a consecutive term.
Thousands of Venezuelans have flocked to the capital to take part in the rally.
Incumbent presidents of Uruguay and Bolivia, Jose Mujica and Evo Morales, ex-president of Paraguay Fernando Lugo, have confirmed their participation in the rally. Foreign ministers of Argentina and Ecuador, Hector Timerman and Ricardo Patino will also attend.
Nicaraguan President Daniel Ortega is due to deliver a speech “with worlds of our love for Hugo Chavez” at the rally, his spokeswoman Rosario Murillo said.
Leaders of Argentina and Peru, Cristina Kirchner and Ollanta Humala, are likely to visit Chavez during their working visits to Cuba to take place later this week.
A Venezuelan opposition leader said the opposition would not protest against the Supreme Court’s decision.
Venezuela's top court endorsed the postponement of Hugo Chavez's inauguration this week and ruled on Wednesday that the cancer-stricken president remained the South American OPEC nation's leader.
The 58-year-old socialist has not been seen in public nor heard from in almost a month following surgery in Cuba. The government says he is in a delicate condition and cannot attend Thursday's scheduled swearing-in for a new six-year term.
"Right now we cannot say when, how or where the president will be sworn in," Supreme Court Chief Judge Luisa Morales told a news conference.
"As president re-elect there is no interruption of performance of duties ... The inauguration can be carried out at a later date before the Supreme Court."
Both Chavez and his heir apparent, Vice President Nicolas Maduro, would remain in the roles after January 10, she added in a judgment quashing opposition appeals for a caretaker president to be named.
Government leaders insist Chavez is fulfilling his duties as head of state, even though official medical bulletins said he suffered multiple complications after the surgery, including a severe pulmonary infection, and has had trouble breathing.
Voice of Russia, TASS, RIA, Reuters, Ekho Moskvy