The actor, 43, discussed Perry's pregnancy and his upcoming wedding to the singer, 35, in an interview with The Sunday Times.
Perry announced in her "Never Worn White" music video this month that she is expecting her first child with Bloom. Bloom is already parent to a 9-year-old son, Flynn Christopher, with his ex-wife, model Miranda Kerr.
Bloom said he's thrilled to be having a child with Perry.
"This kind of joy isn't something you can put into words -- or really wrap your head around," the actor said.
"Obviously we've known for a long time before going public," he added. "As you can imagine, it's such an incredibly precious, private, yet commonplace moment to be sharing with the world."
Bloom said "the whole family is over the moon" about Perry's pregnancy.
"I've been trying not to get too excited and gushy, but I do keep catching myself listening to wistful music, everything from Bowie's 'Wild is the Wind' to the Streets' 'Blip on a Screen,'" he shared. "As well as my fiancée's new single of course."
Bloom and Perry got engaged on Valentine's Day in February 2019. Bloom said they are slated to marry "very, very soon," but may have to postpone their wedding due to concerns about coronavirus.
"I'm not joking when I say that coronavirus might have a play in whether we put things on ice, because we're going to be traveling and we don't want anyone to feel uncomfortable," he said.
Bloom and Kerr were married for two years, while Perry was previously engaged to actor Russell Brand. Perry said in the January issue of Vogue India that she has a "challenging" but rewarding partnership with Bloom.
"Orlando is like a sage. When we first met, he said we would pull the poison out of each other, and we really do. It's exhausting, but we really hold each other accountable," the singer said.
"I've never had a partner who was willing to go on an emotional and spiritual journey like Orlando. It's challenging, because you're facing all the things you don't like about yourself," she added. "It's like a never-ending cleanse."
Bloom is filming Season 2 of the Amazon series Carnival Row. "Never Worn White" is Perry's latest new single following the release of her album Witness in 2017.