Kaley Cuoco, star of 'The Big Bang Theory,' celebrated her 40th birthday on November 30, 2025, with heartfelt moments shared on social media. She marked the occasion with a surprise West Coast party, a cozy East Coast dinner in New York, and a special show at the Paris Theater, where she and fiancé Tom Pelphrey have a meaningful connection. Cuoco, who welcomed her daughter Matilda in March 2023, shared numerous adorable photos of her family, including their first Thanksgiving, Christmas celebrations, and trips to Disneyland. She expressed gratitude for her family, friends, and her life with Pelphrey, whom she got engaged to in August 2024. Cuoco's appearance has evolved from her blonde hair on 'The Big Bang Theory' to a darker, more natural look. She continues to pursue acting projects, balancing her career with her new role as a mother. Pelphrey also shared loving tributes to Cuoco, emphasizing her big heart and their family life. The couple's social media posts highlight their happiness, love for their daughter, and shared adventures, making her milestone birthday a memorable celebration.