The US Tennis Association and American captain Mary Joe Fernandez said the Williams sisters would be joined by Christina McHale and top doubles player Liezel Huber when the Americans host a Belarus side likely to include world No. 3 Victoria Azarenka in Worcester, Massachusetts, February 4-5.
Serena Williams, 30, will make her first Fed Cup appearance since 2007. She was toppled in the fourth round of the Australian Open on Monday in an error-strewn performance against Russian Ekaterina Makarova, although she refused to blame the upset on a right ankle injury she had been nursing since the WTA tournament in Brisbane.
Venus Williams, 31, will be making her first appearance in sanctioned competition since the 2011 US Open, when she revealed she had been diagnosed with the auto-immune disorder Sjogren's Syndrome.
By the time the tie arrives, Azarenka could have climbed to No. 1 in the world, having this week advanced to face defending Australian Open champion Kim Clijsters in the semi-finals in Melbourne.
The winners of the World Group-II tie will advance to the World Group Playoff and play for a chance to compete for the Fed Cup title in 2013.
"I am looking forward to having Serena and Venus on the team for the first time since I became US Fed Cup captain," Fernandez said. "They bring so much to this team, not only for what they can do on court, but the influence they will have on Christina and the rest of the team."