The Big Bang Theory actress posted a shot of a digital billboard displaying the Union Jack flag. The phrase "Pray for Manchester" and the hashtag "#westandtogether" are written on the flag together.
Cuoco simply captioned the photo, "Just wow."
She wasn't the only Big Bang star to discuss the tragedy on social media.
Kunal Nayyar, who plays Raj on the show, took to Twitter to express his condolences and help in the relief efforts any way he could.
"Heart goes out to all the victims and their families in Manchester," he wrote. "I will retweet all relevant information and helplines as I receive..."
Heart goes out to all the victims and their families in Manchester. I will retweet all relevant information and helplines as I receive...— Kunal Nayyar (@kunalnayyar) May 23, 2017
Nayyar then went on to retweet numerous posts aimed to help anyone affected by the incident.
The attack, which is believed to have committed by a suicide bomber, left 22 people dead and 59 injured. The bombing occurred during an Ariana Grande concert at the arena.
"broken. from the bottom of my heart, i am so so sorry," Grande told her followers. "i don't have words."
"My thoughts and prayers are with Manchester," Winter said. "My heart breaks for all those injured and involved, and their families."