Johnston and Bryant totaled 302.10 points to finish second behind only Han Wang and Qulin Zheng of China, who posted a score of 309.90. Australia's Anabelle Smith and Sharleen Stratton took third with 301.20 points while Christina Loukas and Kassidy Cook of Team USA placed fourth at 294.48 points.
Johnston and Bryant's best dive came in the third round, when they scored 70.20 points on a forward 2 ½ somersault 1 twist pike.
"I'm pleased to be on the medal stand, but there are still some things we need to clean up," Johnston said. "There's room for improvement, but this is a big confidence boost for our last meet before Olympic Trials."
The silver medal is the second for Johnston and Bryant in recent international competition, as the two took silver in the 3-meter synchro competition at the FINA Diving World Series stop in Beijing in March. Johnston and Bryant also won the bronze medal in the same event in April on the third leg of the FINA Diving World Series in Moscow.
The U.S. Olympic Team Trials - Diving will be held June 17-24 at the Weyerhauser King County Aquatic Center in Federal Way, Wash.