According to TMZ.com, the 29-year-old wed her beau, 38, during a secret ceremony in Florida a couple of weeks ago. A source told the website the couple attended a friend's wedding recently wearing matching wedding bands, seemingly confirming the news.
The couple have been dating for just over two years, and got together in early 2017 - just months after Kelly broke off her romance with "The Revenant" star Leonardo DiCaprio. She and Steuart were first rumoured to be engaged back in March.
Rohrbach rose to fame as a model, and won the Rookie of the Year Award in the 2015 Sports Illustrated Swimsuit Issue. The beauty later transitioned to acting, appearing in "Two And A Half Men", "Broad City" and "Angie Tribeca".
Steuart is the heir to a huge fortune as part of America's richest family. His grandfather, Sam Walton, opened the first Walmart in 1962, and the family's net worth was listed as being around $163 billion in 2017.
The couple has yet to respond to the reports.