Spielberg voluntarily handed over Rockwell's Russian Schoolroom in 2007 after it landed on a most wanted list.
A judge in Las Vegas ruled earlier this month (Apr10) that the painting, which Spielberg paid $200,000 (£125,000) for, could be returned to the owner - after investigators declared it was a legitimate purchase.
Rockwell's 1967 painting was stolen from a Missouri gallery in 1973, but ownership had been resolved by the time the piece was auctioned in New Orleans, Louisiana in 1988.
New York art dealer Judy Goffman Cutler bought the item and then sold it to Spielberg in 1989.
Jack Solomon, the owner of the Russian Schoolroom at the time of the 1973 theft, sued Spielberg in 2007 for ownership and Cutler stepped in and replaced the painting with another Rockwell piece to protect the filmmaker from legal problems.
She took over as the defendant, and the new ruling means the painting is now rightfully hers again.
It is not known if the piece will be returned to Spielberg, who "never should have had to give it up," according to Cutler's lawyer Gene Brockland.
For the time being, the painting will be displayed at the National Museum of American Illustration in Newport, Rhode Island, which Cutler co-founded, according to the Los Angeles Times.