The 27-year-old blonde bombshell unveiled her incredible hourglass figure on Instagram, showing off her peachy rear for her 893,000 followers.
Wearing nothing but a revealing striped bikini, she could be seen perched on the edge of a pool in the sunshine, dangling her feet in the water.
In the first upload, Kate peered over her shoulder, her back to the camera as she flaunted her gym-honed curves and voluptuous bottom.
She even teased a glimpse of sideboob as she shielded her eyes form the sunshine behind a pair of glamorous oversized sunglasses.
Her golden tresses were pulled back into a sleek bun and a second shot showed her turning to face the pool.
“Sundays in the sun,” she captioned the cheeky post. “P.S. @rioferdy5 how’s Russia?”
Rio’s partner added a smirking emoji to her provocative message for the former England footballer.
Quick to respond, he commented: “Gotta get back ASAP.
“I’m coming hooooome I’m coming,”(sic) he quipped.
Rio wasn’t the only one excited by Kate’s racy snap as her fans flooded to the comments section to compliment her.
“Beautiful,” one said, while another added: “You go girl, show him what your mama gave you.”
“@rioferdy5 she’s a little beaut ain’t she,”(sic) a third chipped in.
A fourth gushed: “Ahahaha love this post and Rio’s reaction! You look amazing Kate and you better be back in Russia by Wednesday.”
Kate and Rio have been dating for a year-and-a-half and she also helps take care of his three children.
Rio will be in Moscow at the BBC studio tonight in his role as pundit for the semi-final against Croatia, as the broadcaster will air highlights of the game at 11.15pm.
Gareth Southgate’s men face a tough test against the eastern European side, who have historically caused England plenty of problems in tournaments.
However, fans will be hoping the high from beating Colombia in a nail-biting penalty shoot-out and then securing a 2-0 victory over Sweden in the quarter final will see them through.
If the Three Lions come out on top tonight, they will go up against France in their first World Cup final since they took home the trophy in 1966.
Tonight’s clash marks the first time England have played in a World Cup semi-final in 18 years.
Croatia vs. England kicks off tonight at 7pm on ITV.