The 43-year-old actress and TV presenter, who remains close to her former love — software tycoon Daniel Reilly, 28, revealed the exciting news on Saturday.
Claire's agent, Jonathan Shalit, released a statement on behalf of the former Strictly Come Dancing contestant, saying that she and Daniel are "absolutely delighted" to be expecting their first child.
"Claire could not be happier," said Jonathan. "To be pregnant and starring in her own show in her home town of Liverpool is all her dreams come true at once."
Claire, who is currently starring in a play she co-wrote at the Liverpool Royal Court, echoed the sentiment in a twitter post, describing her happiness at the success of both her work and private life.
"Thrilled to say my show that I co-wrote Sex and the Suburbs has opened to rave reviews," she wrote. "But the BEST news is I'm 5 months pregnant!!"
Claire's ex Daniel also made an announcement on twitter saying: "I'm going to be a Dad! Love you already son. Blessed."
Claire Sweeney and Daniel Reilly
Claire and Daniel announced their engagement in HELLO! Magazine in April 2013.
The former Brookside actress said 'yes' to businessman Daniel when he presented her with a three-carat diamond ring in a romantic proposal on Christmas Eve 2012.
"I can't believe I'm a fiancée," she said at the time. "The reason I've never married or had children is because I take it very seriously and I hadn't met the right person. I'm a workaholic. I've had a great life and a fabulous career. It would take a very special man to make me stop and want to be with them. Daniel is that person. I was thrilled when he asked me to be his wife."