The 32-year-old model and businesswoman also known as Jordan had placed a bet on favourite Long Run and punched the air as it raced home first past the post - then high-fived her new 25-year-old love.
Katie was apparently a guest of course chairman Lord Vestey at the four-day meet and course managing director Edward Gillespie told The Mirror: 'It's her first visit and she's been great.'
But mother-of-three Katie had earlier struggled with what she should wear to the event, writing on Twitter: 'I'm wearing boring black in killer pink heels. I haven't prepared for this day out to the races x.'
Katie has been using Twitter to keep fans updated on her blossoming relationship with Leandro.
Earlier this week, she uploaded a series of romantic photos of the pair, along with the caption: 'Es todo un tierno. Lo amo,' which translates roughly to 'It's all tender. I love him.'
It had been claimed this morning that Katie and Leandro, 25, were set to marry after the glamour model 'begged' her new boyfriend to propose to her.
But Katie was quick to deny the reports, tweeting this morning: 'Another made up bulls*** story where do these people get there c**p from?'
