Ask any little monster, “What’s Lady Gaga’s legacy performance?” And there’s only one correct answer: The 2009 MTV Video Music Awards.

Now, for the first time in 10 years, fans can watch the iconic show, made available this week on MTV’s YouTube channel, that cemented Gaga’s prominence as one of the most influential performance artists of our time.

The opera-themed medley, featuring her seminal songs “Poker Face” and “Paparazzi,” was theatrically staged amongst gothic architecture, sexy baroque costumes, multifaceted choreography and a mysterious, gushing flow of fake blood, all culminating in Gaga’s own graphic hanging — like meat on a hook (a prelude to her 2010 meat dress).

At the time, the performance was much criticized for glamorizing violent imagery. Even the nuns at Gaga’s alma mater, Convent of the Sacred Heart, were “not amused,” sources told The Post.

But after a decade under wraps, MTV posted the once controversial clip as part of a promotional effort for the 2019 VMAs, which airs this coming Monday, and also ranked the number among their top 10 “mic drop performances,” placing the “Monster Mother” at No. 5.

Gaga’s “Little Monsters” on social media are using this occasion to reflect on the “A Star Is Born” actor’s illustrious career.

“MTV finally uploads this masterpiece officially after 10 effing years,” one fan commented on YouTube. “Can’t believe we in 2019 and still no one can top this performance yet?!” another chimed in.

“Lady Gaga’s performance of Paparazzi at the 2009 VMAs changed me,” tweeted another.

One fan pointed out that the jaw-dropping footage had previously been available through a Vimeo bootleg, but the MTV-official upload was nonetheless validating.

“[I] fully yelped to see that mtv has finally uploaded an hq version,” wrote a longtime follower. “[Shout-out] to that one vimeo link that held it down for years.”

Billboard called the performance a “breakout moment” for the “Shallow” singer, but the debut was outshone by Kanye West, who infamously cut short Taylor Swift’s acceptance speech for best female video by jumping onstage in defense of overlooked Beyoncé.

“On any other year, ‘Paparazzi’ would have been heralded as the show-stopping moment of the ceremony,” Billboard’s Stephen Daw wrote. “Audiences may not have been prepared for it back in 2009, but one decade later, let’s call out Gaga’s twisted, strange performance for exactly what it was — an underappreciated performance art masterpiece.”

Echoed another fan on YouTube, “Children will be studying this in their history books. It’s that legendary.”