Simmons confirmed that she had separated from Hounsou in November after months of speculation about their marriage.
She has since been spotted spending time with Leder while on holiday in St Barts, according to Page Six.
The duo were apparently observed being affectionate together during that holiday. They apparently became close years ago due to Leder's Sun Capital Partners owning a stake in Simmons's fashion brands.
A spokesperson for Simmons commented only that the reality star and Leder "have been friends and business associates for many years".
Simmons was famously married to music executive Russell Simmons from 1998 to 2006. They have two daughters.
> Djimon Hounsou denies cheating on Kimora Lee Simmons