The 46-year-old four-time world champion Holyfield (42-9-2, 27 KOs) will square off with Valuev, 35, dubbed The Russian Giant (49-1, 34 KOs), on December 20 in Switzerland.
The BoxingScene.com website said Holyfield, who has not been in the ring in almost a year, expressed his plans to unify all four heavyweight division belts.
"My goal is to be undisputed champion and not just to win the one title," the website reported quoting Holyfield as saying.
The 7-foot (2.13-meter) Valuev was more cautious in his forecast for the coming bout, calling Holyfield a very difficult opponent.
"First of all, it is an honor for me to fight such a legendary boxer," Valuev said. "Holyfield has vast experience and the fight against him will not be easy."
If the American, who lives and trains in Atlanta, Georgia, beats Valuev, he will become the oldest ever heavyweight world champion. He would then have to meet Ukraine's Klitschko brothers, who hold the remaining heavyweight title belts.
"I think people make too much about age. I haven't fought in a year but I will be ready," Holyfield said.
Ukraine's Wladimir Klitschko (51-3, 45 KOs) currently holds the IBF and WBO titles, while his older brother Vitali Klitschko (36-2, 35 KOs) holds the WBC belt.
Holyfield, who is reportedly paying up to $500,000 a year in child support for nine of his 11 children from previous marriages, said earlier that he was planning to hang up his gloves in 2009 after the bout with Valuev, which he viewed as an additional source of income.
Valuev became Russia's first world heavyweight champion in December 2005 when he defeated Ruiz. Last year he was just a few steps behind the record of legendary Rocky Marciano, who retired at 49-0 as boxing's only ever undefeated heavyweight champion, but lost his title bout to Ruslan "White Tyson" Chagaev from Uzbekistan, suffering the first and the only one as of today defeat.
