The actress - who plays Penny in the hit sitcom - was among the celebrities out to support A Night At Sardi's, an evening in Los Angeles to support the Alzheimer's Association.
It's an annual night of music performances and celebrity guests which benefits the care, support and research efforts of the Alzheimer's Association.
More than $25 million has been raised so far.
Kaley left husband Ryan Sweeting at home and instead attended alongside musician sister Briana Cuoco, who recently appeared on the US version of The Voice.
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