Casey Anthony Rocking Out with Steel Panther Amid New Controversial Doc

Casey Anthony, who was once accused of killing her daughter, seems to be dancing through all the drama without a care in the world ... ahead of her controversial documentary, as evidenced in a newly surfaced video.

The formerly accused and acquitted killer was spotted letting her hair down, and dancing onstage with the band Steel Panther back in March ... and that video is just now making rounds on social media.

The caption of the vid says ... "When you see Casey Anthony at a concert in Fort Lauderdale in March, then her documentary comes out in November" and she looked as carefree as can be.

As noted, the timing is interesting considering she recently opened up about her side of things during her first on-cam sit-down, since being acquitted, for a new Peacock documentary, "Casey Anthony: Where the Truth Lies."

The project's gotten a lot of backlash from people who still believe she bears some blame for her daughter, Caylee's murder.

You'll recall, Casey stood trial in 2011 for killing her 2-year-old daughter. A jury acquitted her of murder, manslaughter and child abuse, and she was only found guilty of lying to cops.