Ozzy Osbourne knew his time was running out during that final Black Sabbath show — and made damn sure his last act was a rock ‘n’ roll sendoff for the ages.

Rocker Tom Morello revealed on Chicago’s Q101 radio station that Ozzy walked into the July 5 “Back to the Beginning” farewell show knowing it would be his last — and just weeks later, the Prince of Darkness was gone at 76.

Morello — who ran the show as musical director — said the mission was simple: make that Birmingham gig the greatest day in heavy metal history.

And by all accounts, he did — with Ozzy perched on a black throne, tearing through “Crazy Train” before reuniting with Tony Iommi, Bill Ward and Geezer Butler for one final Sabbath showdown.

The Rage Against the Machine icon called it a rare moment where 40,000 fans, the band, and the world all poured their love into one man.