The five-year, $20 million deal, which Orakpo signed Friday morning, includes $12.1 million guaranteed.
Orapko became the 11th first-round pick to reach an agreement. After two days of training camp, the Redskins have all of their draft choices under contract and were expected to practice Friday with the entire team.
"This was more nerve-racking than actually being drafted," Orakpo told the team's Web site. "You really want to get in because you know your teammates are there working and you want to get in to get started to have a miraculous season."
Orakpo was the 13th choice in the first round and was selected to add more pass rush to the defense. The plan is for him to be a strongside outside linebacker on run downs. On passing downs, he's expected to line up at defensive end and rush the passer.
He reached the deal on the eve of his 23rd birthday.
"Got the deal done. My pocket's a little bigger. On your birthday, it's always a good thing," Orakpo said.
Orakpo took part in only a few drills during the Friday morning practice, but was expected to be a full participant in the afternoon session.
The former University of Texas star was the Big 12 defensive player of the year in 2008. He had 22 sacks and 38 tackles for losses during his college career.
John Clayton is a senior NFL writer for ESPN.com. Information from The Associated Press was used in this report.