The TV presenter beat actress Kate Beckinsale into second place, while Belinda Stewart-Wilson (Will's mum in The Inbetweeners) was placed third.
Zoo editor Damien McSorley commented: "Holly is no stranger to reader polls counting down the 'World's Sexiest Women', so it is no surprise to see her voted as 'Britain's Hottest Mum' by Zoo readers.
"As she's shown on Celebrity Juice, Holly is always up for a laugh and has a naughty streak, which men love.
"Our Top 10 proves that women can be successful working mums and be celebrated for their sexiness by the men of Britain!"
'Britain's Hottest Mum 2013' Top 10 was as follows:
1. Holly Willoughby
2. Kate Beckinsale
3. Belinda Stewart-Wilson (aka Will's Mum)
4. Liz Hurley
5. Susanna Reid
6. Billie Piper
7. Carol Vorderman
8. Kirsty Gallacher
9. Rachel Weisz
10. Kym Marsh
The full feature appears in this week's Zoo Magazine, on sale now.
Tesco Mum of the Year Awards - photo gallery: