Federation deputy chief Nikolai Proskurin says Armstrong will be making a formal announcement at a news conference in New York today.
He says Armstrong agreed to ride for the Kazakhstan-based team for free for the first year and that his first race will take place in California.
The deal is a coup for the Kazakh team, which was thrown out of last year's Tour de France after Alexander Vinokourov tested positive for a blood transfusion.
Team Astana's leader is Johan Bruyneel,who was Armstrong's team director for all of his Tour de France victories.
"I'm gonna train as hard as I can," Armstrong told Early Show co-anchor Harry Smith Wednesday. "I don't know how competitive I can be, because I've been away for what will amount to four years by the time I get back there next summer. But, the most important thing is we'll take the Livestrong message (to fight what his foundation calls a global cancer epidemic) around the world -- not just the United States, not just Western Europe, but Australia, South America, South Africa, Asia -- and try to create awareness around what really is a global epidemic (of cancer).
"For me, the No. 1 priority is the message. It's making sure that, that not just, as we well know here in the United States, this disease takes an incredible toll. But there's a lot of societies and countries and cultures around the world that don't understand this disease. We try to understand it on a scientific level. There are a lot of other cultures that are just trying to understand the stigma associated with it, the side effects, all of these things that are associated with it we can change over the years."
Couldn't he do it without racing a bicycle at the same time?
"Probably," Arsmtrong conceded. "But I think, if you train seriously and you try to compete at the highest level, it brings that much more attention to it."
Also, he says, training for a recent race made him realize he missed cycling.
Armstong added that there's "no way I could race against" Bruyneel, making his choice of teams relatively easy.
Meanwhile, Australian officials said Wednesday that Armstrong would begin his comeback in the Tour Down Under in January.
Armstrong announced on Sept. 9 that he would return to cycling after three years in retirement and would attempt to win the Tour de France an eighth time.
There were reports in Madrid on Tuesday that 2007 Tour de France winner Alberto Contador of Spain would leave if Armstrong joined Astana.
"I've earned the right to be the leader of a team without having to fight for my place," Contador said in AS newspaper. "And with Armstrong, some difficult situations could arise in which the team would put him first and that would hurt me."
Contador won the Spanish Vuelta on Sunday. Combined with his 2008 Giro d'Italia title, he became just the fifth cyclist to win the three highest-regarded Tours.
"My intention is to stay (at Astana) because I have a contract until 2010, but I have already received a good number of offers from other teams," he said.
Armstrong sought to quell the controversy in his chat with Smith, saying, "Again, our first priority is taking Livestrong global. We're not here to take anybody's job or infringe on the stuff they've rightfully earned. We'll see. I don't know how the season will play out. It's the strongest team in the world which makes it easier for me if I were to be competitive."