The Tipping Point star, who was appearing on podcast White Wine Question Time, revealed that Garraway just likes to talk – a lot.
“I can never finish a sentence!” he laughed.
“Garraway's ability to disregard the fact that someone else is talking when something pops into her head is unparalleled, so I'll be talking, and she will finish the sentence.
“She's not doing it for any other reason, other than something’s popped into her head, and she says what she's thinking. That's why she never lets me finish a sentence!
Listen: Ben Shephard talks about how working through this pandemic has kept him sane
Garraway recently praised her Good Morning Britain co-star for all the help and support he’s provided her with since husband Derek Draper became ill with COVID-19.
She told The Mirror: “For 20 years, Ben’s had to do so much for me but this year’s been another level. He's been trying to do everything he can to help – it’s been a huge pressure on him.
Watch: Kate Garraway's kids saw their dad in hospital over Christmas for the first time
“Working alongside somebody you’re worried about, plus also trying to do the job… it’s a huge thing. I’m aware how tough it’s been for him.”
Shephard said that working with his pal of 20 years is always a challenge as you never know what Garraway may come out with.
“It's very rare that all the words that come out of Kate's Kate Garraway’s mouth do make sense,” he told podcast host Kate Thornton.
“That can often be the challenge is that she's mixing up thoughts from the last half-an-hour and it's all coming out. It's coming out in a sort of splurge.”
Unfortunately for Shephard, he also has to deal with the same thing at home. He told Thornton that Annie, his wife of 16 years, is also guilty of finishing his sentences – but for very different reasons.
“With Annie, it's because she thinks I speak too slowly and I'm wasting time,” laughed the TV star.
“She always thinks she knows the answer to stuff so she will try and finish the sentence without having any idea where we're going with this sentence.”
While this might be annoying to some, Shephard is used to it and says he’s happy to be the “quiet, grumpy one in the corner” when it comes to their relationship.
“I don't mind - we don't need to be talking,” he declared.
“We've been together long enough that the talking is kind of immaterial these days. It's just to fill the space, right? Just buy some shoes every now and again, everyone stays happy!”
Watch: Ben Shephard gets the giggles live on air