The 38-year-old fashion designer cracked a smile as she was photographed on Friday at LAX airport wearing a beautiful sapphire sparkler on that finger.
Simmons looked casual chic, sporting a white V-neck T-shirt, a beige sweater, skinny jeans, sneakers and sunglasses.
A source confirmed to E! News on Wednesday that Simmons and Leissner tied the knot.
While the lovebirds have yet to announce their marriage, Kimora's ex-husband Russell Simmons was the one to initially spill the beans on Twitter.
Russell tweeted to call our a gossip blogger, writing, "All of us love @OfficialKimora but the fact is she is happily married. . Tim is has been family for a while now. #gossipcop...." He followed up with, "Oh. And.. Tim is not Russian. Lol."
Meanwhile, Kimora and Leissner, who works in a senior level position at Goldman Sachs, were photographed back in December during their annual holiday family getaway to St. Barts.
Both were sporting rings on their left ring fingers and were all smiles while walking around the beach with her three kids, Ming Lee Simmons, Aoki Lee Simmons and Kenzo, her son with ex Djimon Hounsou. Russell was also on the family trip.