"All of us love @OfficialKimora but the fact is she is happily married," hip-hop mogul Russell Simmons tweeted Wednesday. "Tim has been in the family for a while now."
No other details regarding the wedding, such as when and where it took place, were immediately available.
People.com said Lee Simmons and Leissner were first spotted together on vacation in St. Bart's during the Christmas holiday.
Russell Simmons, 56, divorced Lee Simmons, 38, in 2009 after more than 10 years of marriage. They have two daughters -- Ming, 14, and Aoki, 11.
Lee Simmons has a 4-year-old son Kenzo with her ex-boyfriend, actor Djimon Hounsou.