"All has been said and done full circle ⭕️ ... back to RED !!!!!" the 39-year-old captioned the post on Sunday, July 11.
The blonde beauty paired the red dress with a black choker and black heels.
Following her recent bombshell court testimony regarding her conservatorship, fans had a mixed reaction to the post.
"These posts can’t be really her, after listening to her powerful testimony," one fan theorized.
"Brit what does this mean," a second fan asked.
"We can’t wait for PROJECT RED ❤️⭕️," another wrote.
Meanwhile, others rushed to compliment Spears.
"Queen of Red ❤️🔥," one fan gushed.
"Gorgerous," another wrote.
Spears has been cryptic about the color red for some time now. The color seems to be a reference to her mystery "Project Red" or "Project Rose" which she reportedly once said was a "personal photo project."
Initially, there were rumors that "Project Red" was related to the Framing Britney Spears documentary that aired earlier this year.
Director Samantha Stark explained that because the documentary was filmed during the coronavirus pandemic, it had to be filmed outside. "If these interviews are going to be outside, I wanted that to be a motivated, stylistic decision. I didn’t want people randomly outside," Stark told Glamour.
"I had been looking at Britney’s Instagram a lot, and I noticed Britney loves roses," she continued. "There are so many posts with pictures of roses and also so many posts of her holding flowers. There’s also this greenery, backyard feel to a lot of her posts. I really wanted the documentary to live in the world of that. I had this rose wall built for the fans, because I was trying to make the amount of roses reflect their relationship to Britney. We did some interviews, and then Britney posted about Project Rose. That is the order of events."
"That's why we used roses throughout the film, as the motif and in connection to Britney. I don’t know that we know much more about Project Rose, but are excited to see what Britney wants to reveal about it," New York Times senior editor Liz Day echoed.
Spears' latest seductive post also comes days after she posted a nude snap that raised eyebrows. The Crossroads actress showed off her bare back, but fans couldn't help but notice that the tattoo on the back of her neck was missing.
"Ok so … I edited out my tattoo on my neck cause I wanted to see what it would look like clean… and yeah I like it better so while you guys are talking behind my back go ahead and kiss my ass haters!!!!!!" the mom-of-two responded.