'Big Bang Theory' star Kaley Cuoco engaged to Karl Cook

"Big Bang Theory" star Kaley Cuoco is engaged after boyfriend Karl Cook popped the question on her 32nd birthday.

Cook, a professional equestrian rider, revealed the happy news with an emotional Instagram post showing Cuoco’s reaction to his proposal.

The clip shows an overwhelmed Cuoco crying while cradling her head in her hands.

Cook’s post was captioned: “Well after nearly two years I finally got up the courage to ask her to marry me. This is the best night of my life and I think the video shows it is the best night for Kaley as well.”

Cook can be heard asking the star: “What’s on your finger, honey?”

Cuoco replies: “We’re engaged.”

But then Cook reminds her: “You still haven’t said yes yet.”

Cook also posted an image of the dazzling pear-shape diamond engagement ring, which drew awe-struck comments from fans.

Cuoco and Cook have been together since late 2015.

The star was previously married to professional tennis player Ryan Sweeting, but the union ended in a bitter split after 21 months.

This article originally appeared on News.com.au