The couple has been linked since last year, but have played coy on the relationship speculation. In December, McPhee and Foster were spotted packing on the PDA in Paris. Then in March, the duo enjoyed a date night at Elton John's Oscar party. McPhee and Foster were photographed inside the viewing party after he first walked the carpet solo. He then met up with McPhee inside where they enjoyed dinner side by side at the same table.
Then in May, the duo walked the rep carpet together at the 2018 Met Gala.
This will be the second marriage for McPhee, who was previously wed to Nick Cokas from 2008 to 2016. And this will be the fifth marriage for Foster, who was previously married to B.J. Cook, Rebecca Dyer, Linda Thompson and most recently, Yolanda Hadid.
A month later, Foster's daughters, Erin Foster and Sara Foster, dished to E! News about their dad possibly dating McPhee.
"We are really happy if our dad is happy," Sara told us, while Erin added, "I love her on Scorpion."
"We love Katharine McPhee. We love our dad. We want our dad to be happy. We don't care who he dates...don't really care how old they are," Sara said, adding, "We don't know if it's her."
Erin said their father is a "very young-at-heart kind of guy."
"Honestly, our friends in their twenties are trying to date him, so we're just proud of him for not doing that," she said. "He's like, 'I draw the line there.' I think thirties, forties is like a respectable age for a man in his sixties."
Congratulations to the couple on the engagement news!