It will be the first game of the season for Staal, who has been out of the lineup with hand and foot injuries.
Staal, whose status had been a game-time decision, made the announcement to the media after the team's morning skate at Consol Energy Center.
Staal had joined his teammates Friday morning for their first and only practice at the temporary sheet of ice at Heinz Field, and in fact lost a shootout competition at the end of the workout.
With Saturday's game time pushed back to 8 p.m. ET, the Penguins and Capitals both took a traditional morning skate at Consol Energy Center.
Staal will make his first appearance in a Penguins jersey since a skate sliced a tendon in his foot during the second round of the Stanley Cup playoffs last season.
He suffered a setback in coming back from the foot injury and missed training camp. Then, when he was about to return, he suffered a broken right hand after being hit by a shot during practice. He had surgery for that injury Nov. 2.
Coach Dan Bylsma said Friday that Staal would likely center a line with Evgeni Malkin, also a natural center, playing the wing. Bylsma said he wouldn't expect Staal to assume his natural workload of 19 to 20 minutes a night.
Information from ESPN.com's Scott Burnside was used in this report.