The guitarist and singer, who learned he'd been voted out of the group in a phone call with Mac manager Irving Azoff, insists he is still owed money from the band - and now he's going to court to get it.
In the suit, obtained by TMZ, Lindsey claims he and the rest of the band signed a deal with Live Nation for a 60-show tour over two years, revealing each member was set to make $14 million (GBP10.5 million).
He tells TMZ, "Over the last eight months, our many efforts to come to an agreement have unfortunately proved elusive. I'm looking forward to closure, and will always remain proud of all that we created, and what that legacy represents".
Lindsey is suing the band and each individual member for breach of contract and breach of fiduciary duty.
The suit comes a day after the publication of a fiery new Rolling Stone interview with Buckingham, in which he claims his former lover, Stevie Nicks, was behind his exit from Fleetwood Mac.
He told the magazine Azoff told him Nicks would never join him onstage again after he "smirked" while she was making an acceptance speech at the MusiCares Person of the Year gala two days before he was fired.
"I may or may not have smirked," he said, adding, "I look over and Christine and Mick are doing the waltz behind her as a joke".
Fleetwood Mac's Lindsey Buckingham Sues Band for Cutting Him from Tour https://t.co/SQw6HFPKjq— TMZ (@TMZ) October 11, 2018
"I don't think there was ever anything that was just cause to be fired," he stated.
Buckingham has since been replaced by Mike Campbell and Neil Finn, who made their debuts as members of Fleetwood Mac during an appearance on "The Ellen DeGeneres Show" last month.
The fired guitarist insists he's far from heartbroken to no longer be a member of the band - he's just upset about the way he was ousted: "The one thing that does bother me and breaks my heart is we spent 43 years always finding a way to rise above our personal differences and our difficulties to pursue and articulate a higher truth," he continued. "That is our legacy. That is what the songs are about. This is not the way you end something like this".