In honour of the special occasion, the 56-year-old TV presenter treated Billy to a fun-filled afternoon at Alton Towers theme park located in Staffordshire.
Over on her Instagram grid, Kate shared a glimpse inside their trip which she dubbed "the best day ever."
She opted to post a gorgeous picture of herself tucking into a hearty plate of food – and wow did she look stunning in her chic cream polo neck.
Alongside the snapshot, she gushed: "Thank you so much to @altontowers the #bestdayever – celebrating Bill's 14th #birthday - hearing them buzzing & screaming with delight was like winning the lottery - despite not being able to believe my 'baby' is 14!!!!"
She went on to say: "Needless to say I was [the] chief bag holder while they went on the rides as [I] am an utter scaredy-cat. But hats off to @altontowers in finding a 'ride' I actually love.
"The restaurant that serves your lunch by whizzing it to your table on a rollercoaster - this is one ride I can get behind!!!!"
Fans and friends flooded the comments section with heartfelt compliments. Reacting to Kate's glowing portrait, one fan remarked: "You look so happy, glad you enjoyed the day," while a second chimed in: "You look gorgeous Kate, so glad you had a lovely time."
A third commented: "I am like you Kate always holding the bags but getting so much delight from the screams of joy of the little people. Happy Birthday to Bill," and a fourth penned: "Haha that's my kind of ride too Kate [laughing face emoji] so glad they had an amazing day!"
Kate shares her son Bill with her husband Derek Draper. The couple are also doting parents to a daughter called Darcey, 17.
It's been a whirlwind year for the family-of-four who have been adjusting to a new 'normal' after Derek, 55, fell critically ill with COVID-19 back in March 2020.
He has been battling with the debilitating side effects ever since and spent 13 months in hospital before returning to his family home.
Earlier this month, the news anchor shared a fresh update, just days after she was awarded an MBE at Buckingham Palace.
Alongside a photo shared to Instagram, the broadcaster wrote in part: "Well what a week, that started with Derek in hospital and ended with Derek in hospital, but with this extraordinary day in the middle. I am so incredibly moved and humbled by the whole experience."
Kate continued: "Tomorrow Derek is back in hospital and of course the daily struggles go on - but the fact that he was able to be part of Wednesday is to be treasured and can't thank everyone in the @NHS and all around him who love him for making it possible.
"I have so many thanks to give but I must make sure I thank @lisaredmanltd for the loan of my 'fit for a king dress' and @missbsmillinery for its matching hat.!! Love to you all and happy Sunday."