"It feels so good to be back after being down just a little bit," the 42-year-old star told the crowd at the Verizon Center in Washington.
Symptoms of the illness include dizziness and loss of balance.
Jackson's manager, Kenneth Crear, said she was feeling "much better" and the North American tour would continue.The Grammy-winning star opened the show with Pleasure Principle, followed by What Have You Done for Me Lately and Feedback.
At the end of the show, the emotional star told the crowd: "I love you DC so much."
Maurice, 28, from Washington said: "She was perfect. If she was sick, she's not sick anymore. She can still do it at 42."
It is Jackson's first North American tour in seven years.
Upcoming gigs include Atlanta, Houston, Dallas and New York.
Jackson fell ill in Canada in September and was taken to hospital.
Five shows in the US and one in Canada had to be rescheduled after doctors ordered the singer to rest.