The former Manchester United and Real Madrid star was a substitute midway through the second-half and showed no ill-effects from his long-standing ankle injury.
"It's a lot better tonight than it has been for a while," Beckham told ESPN when asked at the final whistle about his ankle. "I was happy to get on the field tonight, but disappointed to lose.
"We have to look forward to the next game and work hard. We have a lot of talent in this team and it's now a process of translating that onto the field."
Over 46,000 fans were in attendance to see Beckham's debut, including England boss Steve McClaren, with DC running out rightful winners.
Meanwhile, in Australia, LA Galaxy's first overseas tour game with Beckham is heading for a stunning sell-out in Sydney. The match is to be staged in November and has already sold over 60,000 tickets. Both Football Federation Australia and broadcast partners Channel Ten are cock-a-hoop with the response from Australian fans.