The pair will make issue #18 their last, Snyder has revealed.
"Hey guys - was going to wait until we got a little closer to announce this, but yes, Swamp Thing #18 will be my last issue, and Yanick's too," the writer tweeted.
"To be 100% clear: @YanickPaquette and I have been planning this ending - both an ending for us as creators on the book, and for the storyline we started way back in issue #1 - for a long time. Even before we signed on to do Swampy, we both knew it would be a limited run, as we had other projects in the pipeline we knew would eventually come to pass.
"But the chance to do Swamp Thing, to bring back a character we've both loved dearly since childhood, was just too thrilling to turn down.
"That said, we both ended up staying longer than we'd planned, too, out of love of the character, love for the story we were getting to tell, love for our team, and above all, out of love and gratitude for you guys, the fans who've helped us do something here that many people said was impossible - make Swamp Thing a viable book in the DCU. For that, all of us on team Swampy will be forever grateful to you guys.
"This way I can focus on The Wake, Batman and Superman," he added, "and once The Wake's done (its a maxi) I can return to [American Vampire]. Never want to go above three books."
Animal Man writer Jeff Lemire - who has been working closely with Snyder on the closely connected titles - took to his blog to reassure fans that he "won't be leaving [the title] any time soon".
"I have the series plotted out past issue 30 at this point, and there are a lot of fresh and exciting things coming for the Baker family," he added.
Swamp Thing will arrive on March 6.