"I was very surprised, but you have to make the best of it," DeJesus said.
The Cubs began a four-game series against the Nationals on Monday night with an 11-1 victory.
DeJesus entered the game in the eighth, hitting for third baseman Ryan Zimmerman and received a warm reception from the Wrigley Field fans. He popped out to shortstop, but stayed in the game to play center field.
Though DeJesus provides a veteran left-handed bat for the Nationals, the team, according to a report, may already be looking to move him.
Washington placed DeJesus on revocable waivers Monday, sources told FoxSports.com.
DeJesus has a club option on his contract for $6.5 million in 2014. The Nationals can buy him out for $1.5 million.
DeJesus was buying juice with his wife early Monday afternoon when he missed Cubs president Theo Epstein's call. He returned it a few minutes later and got the news.
"It's one of those moments where you're like, 'Whoa,' " DeJesus said. "Time stops. So I look over at my wife and she's crying. She grew up in Wheaton."
DeJesus thought he might be in the clear after the July 31 trade deadline and wasn't necessarily expecting a waiver deal in August. He couldn't have expected to be playing for the visitors at Wrigley Field in the next four games.
"I couldn't find my way to the locker room," DeJesus said of his new surroundings. "I've never been to this side of the field. It was kind of surreal."
DeJesus, 33, signed with the Cubs as a free agent before the 2012 season. He is hitting .250 with six home runs and 27 RBIs this season. He primarily played center field this season until recently, when the Cubs made prospect Junior Lake the everyday center fielder, moving DeJesus over to left.
"We really like David a lot," Cubs general manager Jed Hoyer said. "I've told his agent and Theo told David directly, we'd be willing to talk to him about bringing him back at some point. He's a good mentor for our younger guys."
The Cubs activated outfielder Brian Bogusevic from the 15-day disabled list to replace DeJesus on the roster.
ESPNChicago.com's Bruce Levine and The Associated Press contributed to this story.