Lovato has serious experience singing the Anthem at major sporting events -- she had the honors at the big Floyd Mayweather vs. Conor McGregor fight back in 2017.

But, her life hit some speed bumps since then and she was hospitalized in July 2018 after nearly dying from an overdose likely caused by Oxy laced with Fentanyl.

Before that Lovato had admitted falling off the wagon after nearly 6 years of sobriety.

Now, Lovato appears healthy and sober and ready to make a public comeback -- and it doesn't get much bigger than the Super Bowl!!!

FYI, if you're one of those degenerate gamblers who likes to bet on the over/under for length of the National Anthem performance ... here's some advice -- Demi's rendition at the Conor vs. Floyd fight went almost 2 minutes and 15 seconds ... so, don't bet on short!