The TV presenter, 30, has kept her daughter relatively out of the spotlight since she was born on 14 March, but couldn't resist posting a photo of her splashing around in the water before bedtime.
In the cute snap, Katie can be seen leaning over the bath washing Belle, who is having lots of fun in her inflatable duck bath.
Alongside the photo, Katie wrote: "Bath time just last an hour! So much kicking and splashing! Belle loves her new Munchkin Duck - we got it today from @kiddicare best thing we have bought her so far! So many smiles :)"
After giving birth to her first child, Katie told fans on Twitter that she and her carpenter boyfriend James were "overwhelmed" with happiness.
Although she has mainly kept her baby out of the limelight, Katie has given fans the odd sneak peek at three-month-old Belle every now and again.
Last month, following an eye operation, Katie - who suffered severe burns in an acid attack in 2008 - was photographed cuddling Belle as she recovered from the surgery.
Katie recently had something else to celebrate when it was confirmed that her TV show Bodyshockers is returning for a new series.
During the documentary series, Katie met people who had modified their bodies with tattoos, cosmetic surgery and piercings.
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