Richardson, 24, surprised the 25-year-old Brandy with an 11 1/2-carat diamond ring valued at $1 million at a reception Tuesday at Los Angeles' Century Club, the magazine said Thursday.
"It was a total surprise for her," said jeweler Jason Arasheben, who designed the ring.
The former "Moesha" (search) star and Richardson were surrounded by their families, close friends and rose petals during the reception.
Richardson's proposal came at time when Brandy's last relationship has been talked about in the media.
Music producer Robert Smith (search) said last week the two were never wed, as she had claimed. Speaking to Wendy Williams, Smith said their supposed marriage was a ruse to protect the image of Brandy, who was then pregnant with their daughter, Sy'rai.
Brandy released a statement saying she was "deeply hurt and shocked" by what Smith had said, adding: "We had a spiritual union and true commitment to each other."
In February 2002, Brandy declared that she and Smith had been secretly wed in 2001. She gave birth to their daughter in June 2002. The couple broke up in early July of last year.
A former teen pop princess, Brandy's latest album, "Afrodisiac," was released last month.
Richardson, a shooting guard, had signed a 6-year offer with the Phoenix Suns worth $45 million that could be worth an additional $3 million with bonuses. On Thursday, the Los Angeles Clippers said it had decided not to match the offer.