Catherine, 44, is said to have moved back into the couple's New York apartment and their relationship is going from strength to strength.
"Michael couldn't be happier," a source told the Mirror, who also reported that the 69-year-old actor was heard telling friends his relationship is "doing great".
"We are doing great," said Michael. "She's doing better than ever."
The Swansea-born actress, who has been married to Michael for 13 years, is also said to have called to wish her husband good luck before the premiere of his latest film, Last Vegas.
The Liberace actor was also spotted wearing his wedding ring at the premiere.
Michael hinted that things were back on track during an interview with Jay Leno earlier this month.
When asked by The Tonight Show host how things were going with Catherine, Michael replied, "Good, I hope. I've been away for a while, but everything should hopefully be on the up and up".
Back in August a representative for the Hollywood couple confirmed that they were taking time apart to "evaluate and work on their marriage".
But Michael went on to say that their separation didn't mean that things were over. "Sometimes people take a little bit of a break, but it doesn't necessarily mean that's the end," he said. "I'm very hopeful".