The British rock legends were accused in 2014 of ripping off a song called Taurus by the US band Spirit.
Taurus was written in 1968, three years before Stairway To Heaven.
Now, the 9th US Circuit Court of Appeals in San Francisco has upheld a 2016 trial verdict that found Led Zeppelin did not copy it.
Stairway To Heaven regularly appears on lists of the greatest rock songs ever written, and the case has been one of the music industry’s longest-running and closely-watched disputes.
Led Zeppelin singer Robert Plant and guitarist Jimmy Page, who wrote the song, could have faced a bill for millions of dollars in damages if they had lost.
The Spirit song was written by the band’s guitarist guitarist Randy Wolfe, known as Randy California, who died in 1997. The case was brought by Michael Skidmore, a trustee for his estate.
Led Zeppelin and Spirit played live together after Taurus was written, and Mr Skidmore suggested Page may have written his riff after hearing Taurus live. He claimed the songs had similar chord progressions.
The case went to a high-profile trial in 2016, at which Page and Plant gave evidence. The jury rejected the claim at that time, deciding the tracks were “not intrinsically similar”.
However, in 2018 the 9th US Circuit Court of Appeals decided the trial judge had made a series of errors and ordered a new hearing.
On Monday, a panel of 11 judges revealed their 9-2 decision that Stairway To Heaven did not infringe the copyright of the Spirit song.