The ChickenShack is a "crispy all-natural and antibiotic-free chicken breast with lettuce, pickles and buttermilk herb mayo," according to the company.
The sandwich will be available exclusively at Shake Shack's Brooklyn locations for a limited time.
It sounds like the chain is testing the sandwich for a larger rollout.
By making the ChickenShack a permanent menu item, Shake Shack would be taking direct aim at Chick-fil-A, the leader in the fast-fast food chicken market. The popular Atlanta-based chainsurpassed KFC last year to become the No. 1 chicken chain in the US.
The menus at Shake Shack and Chick-fil-A are already pretty similar. Both feature sandwiches, french fries and milkshakes. But the only menu item containing chicken currently at Shake Shack is the chicken dog, which is a hot dog made with chicken, apple and sage sausage.
Shake Shack wouldn't be the first chain to go after Chick-fil-A's market.
Taco Bell parent company Yum! Brands has also been testing a chicken sandwich chain, calledSuper Chix.
Like Chick-fil-A, Super Chix sells fried chicken sandwiches, chicken strips, frozen custard, and french fries.
According to research firm NPD Group, chicken meals rose 3% to $5.4 billion for the year ending in March at fast-food restaurants, CNBC noted.
Is there a Shake Shack near you? Check out these locations:
Shake Shack just launched a Chick-fil-A killer — and it looks amazing
A general view of the restaurant Shake Shack in Washington, DC, December 30, 2014. The fast-food chain, started by celebrity restaurateur Danny Meyer, filed to go public on December 29, 2014. Backed by private equity firm Leonard Green & Partners, Shake Shack is a self-described modern day roadside burger stand whose vision is to stand for something good. AFP PHOTO/JIM WATSON (Photo credit should read JIM WATSON/AFP/Getty Images)
NEW YORK, NY - AUGUST 18: People wait in line at Shake Shack on August 18, 2014 in Madison Square Park in New York City. Shake Shack is allegedly considering going public and holding an initial price offering (IPO). (Photo by Andrew Burton/Getty Images)
FLUSHING, NY - MARCH 29: Spectators line up to get food at the Shake Shack and Blue Smoke during the Georgetown and St. Johns game at Citi Field on March 29, 2009 in the Flushing neighborhood of the Queens borough of New York City. This is the first event to be held at the new Citi Field. (Photo by Ezra Shaw/Getty Images)
CHICAGO, IL - JANUARY 28: A sign hangs over the entrance of a Shake Shack restaurant on January 28, 2015 in Chicago, Illinois. The burger chain, with currently has 63 locations, is expected to go public this week with an IPO priced between $17 to $19 a share. The company will trade on the New York Stock Exchange under the ticker symbol SHAK. (Photo by Scott Olson/Getty Images)
Cool beans! We're partnering with our neighbor @joecoffeecompany at Philadelphia's University City Shack on a special edition affogato. Get your fresh-made vanilla frozen custard at the Shack, then head next door to add a shot of espresso. For a limited time only, at University City Shack only. #shakeshack
Friends with benefits. #shackfan pic by @klpollack. #shakeshack
Shake before you leap. #shackfan @bricavaco's love for Shack knows no bounds. #shakeshack
Lookin' fly in the 215. Thanks to @muralarts, @_david_guinn & @termini_bros for helping us officially dedicate the #Philly Shack's custom-created mural. More pics on our FB page. Raise the roof! #shakeshack
Cookin' on Michigan Avenue. Hope we see you soon at our newly opened @chicagoathletichotel Shack in the Windy City! #shakeshack
Austin, you rock! Thanks for the big ol' Texan welcome for our new Shack in #ATX. Check out more photos from our housewarming party (5/4) and opening day (5/5) on our Facebook page, Tumblr, and Stand For Something Good blog. #shakeshack
Doors are open in Bridgewater, NJ! Our team's psyched to open our first Central Jersey Shack at the Village at Bridgewater Commons. Hope we see ya soon! #shakeshack
This winter's brutal, but there's no way but up from here. Newbury Street Shack from below by our own @brett_lindsey #shakeshack #boston
Let's do this, Dedham! Shake Shack is now open @legacyplace. Get ready for ShackBurgers, Greater Boston. #shakeshack