"This ride has been a dream come true and as life changing as it gets. No matter when it was going to end, my heart would have always been broken in two," Cuoco wrote alongside a sweet pic of the cast. "Drowning in tears, we promise to bring you the best season yet."
"To the fans, our crew, families, Chuck Lorre, Warner Brothers, CBS, and everyone who has supported us for so many years, thank you. We are goin out with a bang ? @bigbangtheory_cbs," she added.
Cuoco has starred as Penny on the CBS hit since it premiered in 2007. Big Bang will air its final episode in May 2019, ending its run as the longest-running multi-camera series in TV history, with a record-breaking total of 279 episodes. Co-stars Jim Parsons, Johnny Galecki, Simon Helberg, Kunal Nayyar, Melissa Rauch and Mayim Bialik have yet to comment on the news -- though Rauch celebrated the first taping of season 12 with the cast on Tuesday.
ET caught up with the cast at PaleyFest in March, where they revealed the future of the series was up in the air. Cuoco, however, was hopeful about continuing the series. "I love being a part of the show and I think it'd be really stupid to say no. There's just nothing better. Season 13 does sound kind of cool," she said.
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Octavia Spencer Jokes She'll Return to 'Big Bang Theory' Under One Condition
In a joint statement on Wednesday, Warner Bros. Television, CBS and Chuck Lorre Productions promised to bring an "epic" conclusion to the show.
"We are forever grateful to our fans for their support of The Big Bang Theory during the past 12 seasons," the statement read. "We, along with the cast, writers and crew, are extremely appreciative of the show’s success and aim to deliver a final season, and series finale, that will bring The Big Bang Theory to an epic creative close.”
The Big Bang Theory's final season premieres Monday, Sept. 24 at 8 p.m. ET/PT on CBS, before moving to its regular time period on Thursday, Sept. 27 at 8 p.m. ET/PT. See more on the show in the video below.