Australia battled the Americans on even terms throughout much of the first half on the strength of 3-point shooting but the United States eventually opened a 12-point edge at the break.
Bryant and Carmelo Anthony then hit 3-pointers to start the third period and the United States surged to a 69-43 lead before the Australians could manage their first points of the half.
"We understand we are not going to break things open in the first period," Bryant said. "We have to wear teams down. We come in waves. Usually in the second or third period is when we can bust things open."
Bryant scored 25 points, hitting 10 of 16 shots from the field, and LeBron James had 16. The Americans shot 57 percent.
The United States will take on defending champion Argentina in Friday's semifinals. Argentina edged Greece in the last of the quarterfinal games 80-78, surviving a last second three-point attempt by Vasileios Spanoulis. Argentina defeated Italy in the Athens final.
Earlier in the day, Lithuania ended China's medal hopes with a 94-68 win and Spain fought off Croatia 72-59. Lithuania and Spain will play in the semifinals.