"My love. My life. My family. My future. @bader.shammas #love," she captioned the series of snaps, in which she offers a look at her diamond ring.
The star disabled comments on the post, but it received more than 130,000 likes in the first two hours, and fans were quick to offer their congratulations on Twitter.
“So so so happy for you guys, congrats!!!!,” one fan wrote.
“This made me tear up," another wrote. "This is what life is about, I am so happy for you. Life is about the adventure. It’s about the connections we create. Sending all of the love and light to you both.”
Shammas also shared the post on his Instagram account.
Lohan, who has called the UAE home for more than six years, has kept her romance with Shammas largely private, however, she has shared some images of the couple with her nine million followers in the past.
Shammas, a financier who also lives in Dubai, is assistant vice president at Credit Suisse. He and Lohan were first spotted together at a Dubai music festival in early 2020, before the start of the pandemic.