The mum-of-two wore a form-fitting long sleeved, zip front black dress with khaki green lace up boots at the airport.
The Keeping Up With The Kardashians star wore her dark hair slicked back into a glossy ponytail and finished off the look with a pair of dark sunglasses and a smart black bag.
Her husband Kanye West looked equally striking in a t-shit tribute to his late mum, Donda West.
He first wore the white t-shirt, emblazoned with his mother's face and the words "In loving memory", backstage at his Yeezy Season 3 fashion show at Madison Square Garden in New York.
The back features a picture of Kim's late father, Robert Kardashian.
Kanye, 38, teamed the moving t-shirt with a denim jacket, dark jeans and trainers.
He later put his arm protectively around his wife as they made their way through the airport.
The pair had been in London for the weekend where Kim, 35, had attended a discussion at the Vogue 100 Festival.
She was part of a panel talk held at the Royal Geographic Society, entitled, 'Fashion, Friendship and Fabulous lashes.'
She also enjoyed a smart dinner with Kanye in Mayfair, even stopping to pose for photographs with delighted fans.
Kim later shared a Snapchat from Heathrow of her sister Kendall Jenner's Este Laude campaign.
Filming the advert which features Kendall, Kim said: "It's my sister! I'm at the airport. I'm so proud."
On Friday night (May 20) Kim shared an intimate Snapchat of her in bed with Kanye, complaining of jet lag.
She said: "I can't sleep. This always happens to me while I'm in London."
She later joked about her husband's snoring and filmed him, writing: "His noises though."
She said: "This is so unfair. He's like passed out. Do you hear him snoring?"