It's the next logical step in Miley Cyrus' career ... PORN ... and one company just offered the singer a cool $1 million ... TO GET BEHIND THE CAMERA ... TMZ has learned.

Adult retailer GameLink is NOT asking Miley to strip naked, but they definitely want to get her elbow-deep in a hardcore sex scene ... from the director’s chair.

GameLink fired off a letter to Miley's people on Wednesday, offering her $1 mil for the directing gig (including full creative control) and even took a pot shot at Sinead O'Connor while they were at it. Burn. Check out the letter.

Now ... here's our list of Miley porn name ideas: 1) Wrecking Balls, 2) Dirty Twerk, 3) She Can't Stop, 4) MTV VMA-nal ...