Houston was buried on Sunday in her hometown Newark, New Jersey.
Brown controversially stormed out of the ceremony at the beginning following a seating dispute and not being allowed to sit near his daughter Bobbi Kristina.
The star left the service in tears and later released a statement saying he was moved by security three times.
But he sparked even more controversy later that evening, by turning up on stage with his band New Edition at the New Jersey Performing Arts Centre.
Between songs, Brown, 43, admitted to the capacity crowd: “The past few weeks have been terrible.”
After singing several of his hits, including My Prerogative, he told the crowd: “I lost three great people in my life in the last year, but nothing makes me happier than to be here with you.”
But some believe his concert appearance so soon after the show was insensitive.
Concertgoer William McGarrah said: “I grew up on New Edition, and want to see how Bobby responds. [It was] a little insensitive, and shows how much he needs the money. I thought he would take time off to be with his daughter.”
Bobbi Kristina, 18, was reportedly found taking drugs after her mother’s funeral.
Houston was found dead last Saturday night at The Beverley Hilton Hotel in Hollywood.