Susi, who was battling cancer, died early Tuesday morning in Los Angeles. She was 62.
The actors took to social media to express their grief over demise.
Posting a black and white photo of Susi on her Facebook page, Cuoco captioned it, "Rest in peace hilarious, adorable, sweet Carol Ann Susi. You will forever be part of the Big Bang Theory family."
Bialik tweeted, "Beloved Carol Ann Susi passed away, yes. The voice of Mrs wolowitz. Oh Carol Ann." Actor Kunal Nayyar wrote, "My heart is broken. I will miss your smile. Your spirit is forever with us."